I was barred from my college campus for suicidal ideation and I'd like to sue?

Everyone who I have described the situation to believes that I was treated very unfairly. Also, the school administration claims that they were following protocol, but I know for a fact that there have been inconsistencies in how I was dealt with and how other students in similar situations have been dealt with-because those other students are friends of mine. Additionally, the way that they handled certain aspects of my situation was irresponsible. Several other students have been affected adversely by this policy, and after what has happed to me, my friends think that I should sue. I am 18 and I have absolutely no money, but I do have a good case. How should I proceed? And how long do I have to go about doing this? Is an attorney necessary, and if so, how do I find a free one? My entire academic career is at stake, here.