Advice...Encouragement? How can I enjoy my sweet 16!?

Hey, Here's some backround information: I'm 15, I LOVE to run, and my stomach is the worst organ on the face of this earth! I have iritable bowl, acid reflux desise and my stomach hates everything it meets syndrome.

I Run for my track teams, and this winter my stomach was so bad I was getting only 1400-1500 cals, wich is soo soo not enough with my activity. I had two week viruses in a row, lost about 10 pounds and havn't been able to regain untill now.

I went to a nutritionist, and she wouldnt let me do ANY ACTIVITY. I followed her directions, but went crazy. I have really, seriously, no other way to deal with stuff than exercise.

I gained 2 pounds the first two weeks, week three I weighed myself, and I was already at my "running weight" (+5 lbs) (when I'm allowed to start training again!) but my weight is constantly fluctuateing!! between 85-90 and its soo spontanious and random. I need to be 90 pounds tuesday so I can start my regular life back, I dont care how much i have to eat, I HAVE TO RUN!

My sweet 16 is this upcomeing saturday, and if this weigh in goes bad, I know it will wreck it. :-( help me get through this!

PS I dont have an ED, or any problem with gaining weight, I LOVE food,cooking, and eating so other than the horrible bouts of diareah and stomach cramps, bloating and overall unhappyness, I'm enjoying all the food I get to eat!

So someone give me advise, last thursday I was 89.5 at like 11 am, 2 days ago I was 84 first thing in the morning, today I was 85 1st thing when I woke up, I'm 90 now, and the thing thats NOT FAIR is all my weigh ins have been at the nutritionist on a wednesday at 6 pm. this one is at a different doctors, where I'm going for annother stomach test, first thing in the morning and I'm not allowed to eat or drink before the test. AHHH!!??