I think my boyfriends cheating on me..

Idk why I have a deep and very strong feeling my boyfriend is cheating on me... I don't know why?? I haven't found anything on his phone or anything, well I haven't hung out with him in like a whole week.. but he seems very distant and "busy" and I've asked him and he's said no, he didn't really get defensive but I just have a STRONG AND I MEAN STRONG like I weird feeling in my stomach... and I've had dreams where he's cheated on me or he's talking about having sex with other girls and I know they're just dreams... but yeah idk what to think.. I think I'm just being a crazy girlfriend...