What's wrong with him and how can it stop?

My husband is 32yrs old, but i'm starting to think that he's mentally challenged. For the last couple of years he has acted so childish, bad mannered and rude. He will blow his nose by squeezing one side of his nose while expelling mucus out the other nostril and he does this in public as well. He'll clean his nose with his shirt at times, he'll raise his shirt midway and scratch his belly which by the way is not flat. He'll burp and even p gas and all of this in public too. I used to think it was because he was raised in a very poverty stricken part of mexico, but his mother and sisters do not act like this. I'm embarred to go out in public with him. I so desperately want him to stop, but he won't. Please help i am seriously starting to hate him and have even thought about leaving.