You just don't get fevers for no reason, something is going on inside of you like an infection. If you think you have crohns, then a fever is an indication you might have inflamation in your gut somewhere and the longer you don;t treat this, the more damage it will do and the harder it will be to put it into remission.
Before I was first diagnosed in 2007 with CD, I had a low grade fever off and on for 6 months with bouts of D off and on. I ignored it, chualking it up to my food or something else, I just thought if I ignored it long enough, it would just go away.
Well, after 6 months, two massive rectal fistulas appeared near my anos , which in turn lead me to being diagnosed with CD in the colon. If I had went to GI the second I started seeing symptoms like fever and strange bms, I could have saved myself a lot of pain and anxiety.
I suggest you go to GI and ask for an colonoscopy or a MRI of your gut to know what is really going on.
As soon as I was diagnosed, I went On the SCD diet and both my fistulas healed up after 5 months and I have not had a symptom from my CD since, and I still follow the diet.
One thing you can try is changing your diet and see if this helps. Start by eliminating all sugar and foods with sugar since sugar adds to inflammation in the gut. But also, I would see a GI and not let this get to far along. The earlier you find CD before it has done much damage, the better chande you have of putting it into permanent remission like I have.