I'd be interested in knowing what your grandson's definition of a "tummy ache" is. I often tell people, "Well, my stomach hurts today" just to AVOID telling them the REAL issue at hand. Sometimes that sort of stuff is just WAY TOO MUCH INFO to give and it's easier to say "tummy ache".
I can't imagine having had this disease start in on me when I was a teenager. What a nightmare. When I get really sick, I always think of those younger than me who've had to deal with this AND try and get an education at the same time. I can't even wrap my brain around it - trying to understand what's happening at THAT early of an age? I don't know how I would have made it myself.
I think it'd be hard to know for sure if your grandson is "playing the system" or not. On the one hand, he's a 13-year old boy! Need I say more?
On the other hand, this disease is SO unpredictable. I know for me, I can be feeling like a million bucks one minute and the next minute be doubled over in pain driving myself home so I can poop and vomit at the same time in the privacy of my own bathroom.
There are times I haven't been able to make it to the bathroom fast enough. Usually after a spell like that I'm physically drained, feel like crap and am useless the rest of the day. However OTHER TIMES, I can go through one of those "spells" and 10 minutes later, feel as fine as I did just 10 minute before.
U-N-P-R-E-D-I-C-T-A-B-L-E!
And that's just during a SPELL. A spell to me is just a bad moment during a time of remission. But during a FLARE...GOOD LORD. Flares are awful. 24 hours a day, 7 days a week. My last flare lasted for TWO YEARS. Medications helped some which is about all the doctors can give to help you through a flare. But they can't stop the flare. The body has to do that on it's own. There is no CURE for this disease.
If your grandson has the typical Crohn's Disease symptoms of gas, diarrhea, bloating, nausea, etc. I would think emotionally it would be extremely hard for him to go to school and hang out with friends outside of school. Even as an adult, that's a hard thing to deal with at work and in social arenas. I lost my entire circle of friends years ago when I had to stop going out with them on a regular basis because of my symptoms. They just gave up on me because they didn't understand what I was gonig through. One of them actually said, "I don't see what the big deal is - if you gotta go to the bathroom, just get up and go!" They couldn't comprehend the multitude of symptoms that go along with something as simple as LOW IRON caused by blood loss through this disease...add arthritis pain, mouth sores, massive fatigue and cramping ON TOP OF the embarrassing gas and diarrhea...UGH! It's MORE than just a bowel movement to us. This disease affects EVERYTHING on and within our bodies.
When I was 13 and in the 7th grade, my stomach used to hurt every morning by 2nd period. I didn't learn a lot in Biology that year. I was given Librax back then because the doctor thought I was anxious about being at school. Now, 25 years later, I'm taking the same drug to relax my colon (and they are getting ready to take this drug off the market!)
So I wonder now if I was having extremely LIGHT symptoms of Crohn's Disease back then in the 7th grade and it just didn't start to really affect me until my 30's.
As for diet, I'm a firm believer in healthy foods...organic, all-natural...staying away from sugary, processed foods is best for everyone, with or without Crohn's Disease. My GI will say food has absolutely nothing to do with the CAUSE of Crohn's and that you should just simply stay away from foods that bother you (which again, goes for everyone).
When I'm in a FLARE, I stick to a low-residue diet: plain pasta, white bread, plain yogurt, Ensure, etc. BUT when I'm NOT in a flare, I can eat absolutely ANYTHING and it will not bother my Crohn's Disease at all. Bring on the Mexican and veggie pizzas! I still stay away from soft drinks & sweets when I'm at home, but if I'm out and about I'll eat those things, assuming I'm not already flaring, and they will NOT cause me to be sick. The only time that kind of food causes me to get sick is when I try eating it when I'm ALREADY in a flare.
My first inclination is to tell you to give your grandson a break. If he's having even mild symptoms of this disease, that's enough to make anyone shy away from social situations! If you know he's having diarrhea all the time, surely you can understand why he'd be reluctant to go to school, of all places! (UGH...I can't imagine getting sick in a school bathroom). BUT, having said that, I also understand your obvious concern that he's not getting his education. It's a very fine line for sure for you to be walking.
Just don't under-estimate what this disease can do. Every day, I make sure I wear something with pockets so I can put a plastic bag in it. I never know when a sick bowel movement is going to come over me. When the sick ones come, so does the vomit - at the same time. So if I end up in a bathroom without a trash can, I need the plastic bag. Gross, right? But it's just an example of something simple that I mentally deal with every single day.
Your grandson might be dealing with that sort of thing, too...and I imagine a 13-year old boy would be embarrassed to talk about ANY of the symptoms that go along with Crohn's Disease to anyone - particularly his grandmother!
My point being that although you might see him jumping around and playing, there may be many times he's in pain and just not saying anything about it. Gosh, I do that all the time myself (just this morning, in fact, I pretended that I wasn't having awful intestinal cramping while I was talking with my boss in his office).