I need advise help!!

I think my boyfriend is cheating. We have a 1 or old son together but he doesn't act right considering we've been together 3 years. He thinks he can just go through my phone but if I even look at his he freaks out. He wont let ne see it or go through it. Plus I recently went to the obgyn and found out i had an std and I haven't been with anyone else. Im waiting on him to go to the doctor to find out if he has it because we haven't had sex in almost 3 weeks to a month. What do you guys think?