Advice please!

Me and my bf have been goin out for over a year now. But recently he keeps sayen that hes unhappy and he doesnt know why and ive asked him is it me and he keeps telling me no. He says that he feels like his mental health isnt right and he constantly feels like he wants to cry. I dont know what to say to him to help him and he says that he gets overwhelmed and suffocated at times when he cant get time to himself. I dont know how to help him and he just seems to not know how to help himself. Ive told him to go to a doctor and see what they say but he doesnt seem to want to go. Says that he feels as if he has bottled all his emotions up. How can i help him because i dont want our relationship to fail. We also havent had sex in a while because i am just too afraid of getting pregnant and i keep getting upset over this and crying myself because i dont know what to do :( please help!