I can relate with your story to a degree.
When I was about 19 I experienced a rather sudden onset of IBS (although at the time I had no idea what was wrong with me.) My family and even my primary care physician at the time chalked it up to me being overly anxious. Yeah..when you're afraid of pooping your pants everyday, I'd think you'd be a bit anxious too!
Anyway, the IBS triggered extreme anxiety in me. I was quickly labelled a head case by my fam and my docs. They would just tell me to relax and that the pain was all in my head. Psychosomatic I think was the word that was used. It was terrible. I beat myself up all the time thinking I was causing my problems. The doc put me on Zoloft as well. It didn't agree with my tummy, but it zapped those panic attacks in their tracks. I went off it because I didn't like the side effects and I felt my parents were embarassed I was on an a/d. They never wanted to talk about it. I felt very alone and scared.
I've suffered from both IBS and anxiety ever since (I am now 28) and only within the last couple of years have my parents truly understood what I am going through on a daily basis. It took having terrible panic attacks in front of my mom and being nearly hospitalized from extreme abdominal pain due to my IBS and biopsies in my colon that revealed abnormal cells that made them wake up to the fact there was something organically wrong with my body that was causing me to go nuts.
I brought them in to talk with my gastroenterolgist about the severity of my IBS and during that conversation we delved into the impact it had on my mental well-being and quality of life, i.e. it was causing me great mental distress and anxiety. This finally made them realize they needed to approach me with more sensitivity.
Not to bash my folks. They are the kindest, most loving people around and have supported me through everythinng. I am truly blessed. However, they have never personally experienced anything quite like this and since I have always demonstrated the ability to be capable and excel at whatever I attempt, they figured I could control this as well. I'm a lawyer. I'm therefore a professional problem solver and I"m good at it. I just can't solve my own problems all the time. That was hard for them to understand.
Long story long (hehe) I think you should try to educate them on the subject of your anxiety. Maybe give them literature on the subject that educates them about your condition, or gives them advice on how to deal with a loved one going through what you are experiencing.
My guess is that like my folks, what they don't know they can't understand. It breeds not only ignorance about your struggles, but a sort of unintended apathy. If you are young, and I am guessing you are, then it's also hard for parents to think that their healthy young kid can be experiencing something like this. Maybe your mom thinks she can "scare" you into acting better. I don't know. If your doc is willing, take your mom and dad in to meet with him/her and have the doc explain what is going on , what to expect, how to help you get better.
Much love to you. I know how tough this is.