HELP ME PLEASE!

Okay lady's I need your help!? Lately we and my man have not been having sex... we had sex for the first time the other day is 3 monthes and it was great like always but he never wants to have sex he says he don't have the urge to and he is 28 and I'm 23 and he has MS do you think that has something to do with it or do you think something els is going on?? I know he's not cheating on me or anything like that so I'm at a lose and lately he been just lashing out for no reason then a little bit later he acts like nothing ever happened!? I'm at a complete loss idk what to do please give me any advice you have!!