looking for more advice

I have a gut feeling something is off in my relationship. What do I do? Hes been acting very different but I dont have a suspicion of cheating. Please give me advice on what to do. I have tried bringing it up and hinted my stomach feels strange he just thinks im not trusting him/jealous. I need answers from him or some conversation and he hasnt reassured me that everything is okay. How do i confront him on this?