Why do I keep thinking that I smell bad?

I shower every morning, wear clean clothes, wear deodorant and even use a bit of body spray. I listerine and chew minty gum so I don't have bad breathe but now that it's summer every once in awhile I will catch a whiff of something during the day that smells like b.o and I keep thinking it's me. Other people don't seem to think I smell, and are quiet close to me at times and even tell me I smell good. I think I have some phobia of smelling bad or something, but if I don't smell bad why do I keep smelling something weird on me?