Think I have crohn's but doctor won't send me for colonoscopy!

Hi, I'm new to here so hello everybody! 

I was diagnosed with ibs around the age of 15 and until last summer when I was 18 I hadn't had much problems. I was very ill with stomach pains for weeks and doctors didn't seen to be too bothered, I was given around five different diagnosis from different doctors and given different tablets. Eventually, I couldn't handle it anymore and was taken into hospital. At this point I weighed 7 stone having lost nearly 2 stone in just the few weeks I was ill. They took blood which showed high inflammatory yet only sent me for an ultrasound and then discharged me. They put me on lansaprole for a ulcer which my doctor took me off when I moved to Cambridge for university stating that there was no proof I had an ulcer so shouldn't be taking them. Yet he didn't send me for any tests apart from to check for celiac. 

Once again, a year later I'm having a very bad flare up. They have been happening on and off for months and my ibs tablets do nothing at all. 

My main symptoms are:

Stomach pain - below my sternum, top of the stomach, usually towards the center. 

Diarrhea - blood and mucus, freqent and urgent.

Skin rash - pinpoint red flat spots in clusters as well as a crusty rash around nose that iv had for years. 

Small ulcer - in my mouth on the bottle lip, clear in colour.

Sickness.

Please help, my doctors seem to think I am a hypocondract, however this is seriously affecting my life, work and university. 

I als

I also get pain when anyone just lightly grabs me or touches me too hard 

Start making some noise for a referral to a gastroenterologist.  Go and see a different GP and if need be make a complaint.  Passing blood shouldn't be ignored and isn't a symptom of IBS