LOL do you really, honestly think you're imagining them? If I feel like that I usually try to take 5 mins and sit back and concentrate on the nausea, or dizziness or whatever and ask if I'm honestly imagining it, if I could just shake my head, focus hard on something else and it'd be gone, or whether I am actually feeling it. If you still feel the same in 10 mins then it's probably not in your head!!
xxx