relationship sex help

My husband and I have been married for almost two years up until I gave birth to our daughter our sex like was fine and then it suddenly stopped. He would never want to have sex it would literally only be like once a month. I have dealt with that the best I could and try to take in consideration that he does have a high stress job but it has been four months without anything! And a girl can only do so much for herself. Yesterday I tried to talk to him about it to see what was going on and he can't give me an answer. I have started having dreams about him cheating witch makes me feel absolutely crazy I have told him about these dreams and he just tells me nothing's is going on. What do I do?!?!?
Update: I have tried the whole spicing things up. So far it hasn't worked. I sent him this picture and got no response.