Hi Richid,
I too am a 3rd year mechanical engineering student at university and totally understand what you are going through.
What i would say is that firstly, i found my university wasnt great with toilet facilities (especially in the campus that i study at) and therefore i wrote the student services a quite blunt e-mail explaining my situation. They soon took action and i can gladly say that the facilities have been improved!
Secondly, i found that when i started uni, i was shy and embarrased to talk to anyone about
my condition, until i decided i had enough and spoke to my closest friends on my course! They were/and are still very supportive of my condition and strangely enough, another student on my course too suffers from colitis. If theres ever a case where i have missed any lecutres/materials, the other students know why and are good enough to get me the copies of the materials i have missed. So what i would say is dont be embarrased and let them know!
In terms of going out/social life, i found that going out with friends and enjoying myself can be achieved without alcohol. If i am on treatment, then i tend to stay at home and my friends dont mind and sometimes join me!
If you really are struggling with the condition, i would say speak to your student services department, they can do a lot to help you out including giving you extra time in exams etc. I hope your situation soon improves and you start to enjoy your time at university because let me tell you, it can be some of the best years of your life, even if you suffer from colitis! Try make the most of it, i know its easy for me to say, but dont let colitis take control of your life! I certainly refuse to let it.
Let us know how you get on.