Earl Morning Diarrhea / Stomch pains

Hi, at about 13-15 years of age i was never able to eat any breakfast as my stomach was always full / hurting, but i never had any problem with this as far as i remember. Now im 20 i still have the same kind of problem. However, whenever i wake up later, 10 onwards say my stomach feels fine, just the usual morning movement. But, if i wake up early, for instance today i woke up at 8.30 and after 10minutes of being awake my stomach was really bad and had Diarrhea. It is starting to effect the amount of lectures i go to as my stomach can take awhle to settle with/without tablets.

If ive ate a lot the night before then some nights i am likely to wake-up around 2am with a very bad stomach and it can take two trips to the toilet untill i can sleep again.

I havent been told ive got IBS but i wonder sometimes. The last time i went to the doctors they weren't helpful at all and just told me to watch what i eat. Im not on the most healthiest of diets, but im not an unhealthy eater either. I usually eat the same amout than my g/f and she never has any problems.

Thanks for any advice.