Can I sue my son's former private school for discrimination?

My son who is currently in 8th grade has had severe asthma since he was 5. The private Christian school that he attended since kindergarten knew about his medical history. The school has a very intense sports/athletic program. The school had no problem with my son dressing out, and participating his best in physical education cl, until this year. The way my son had always participated was that he would do everything normally with no problems unless he had an asthma attack, which he would then use his inhaler and sit down and not participate the rest of the cl. This year was just like always same P.E. routine, until the coach/teacher of the cl got angry with my son when/if he had an asthma attack. When this would happen the coach would send my son to the dean of middle school students, who himself is the head football coach (who favors EXTREMELY athletic people.) The dean then would get angry and yell at my son and would even threaten to have the headmaster expel him. The situation got to the point that as soon as my son got to P.E. cl the coach would send him to the dean with no explanation, and the dean would continue to be extremely rude and hateful to my child. Finally I called the middle school principal, upper school principal and headmaster to explain what was happening. The calls made the situation worse, the more powerful people then got involved and proceeded to have an expulsion meeting. At this point I still could not be given a reason as to how my all "A", academic award winning son who the school valued greatly went from being the great student to being expelled. I finally received word that the expulsion was because of defiance to the P.E. coach and dean. This was for not participating when having an asthma attack. The guidance counselor (who I personally knew) called me to say that she personally recommended I withdraw my son from the school before my son was "officially " expelled. The guidance counselor said it would be much easier to get my son into another private school if I withdrew than was expelled. I then made the tough decision to withdraw my son from the school he loved and the friends he had known his whole life and asked for the withdrawal papers to be drawn up. I asked the guidance counselor how this happened and she said that she had no idea and that the school cared more about athletics than academics and Christian values.I just withdrew my son from the school in September and he is now enrolled in a new private school. My son wants to return to the school so badly, but can't because basically he has asthma. So can I sue the school for discrimination against students with medical problems?