I sometimes wake up at night feeling very nauseous and needing to go to the bathroom. I also have the same problem if I am outside or in a place where I am in sunshine and heat. I begin to feel nauseous, I become dizzy, I begin to sweat and develop a severe headache as well as needing to urinate. I don t understand the relation between the need to urinate and the nausea. I have been diagnosed in the past with interstitial cystitis. I have not had treatments for this condition in several years, but could there be a relation between that diagnosis and the symptoms I am having now. If not, could you please give me possibilities for any other condition that might present the same symptoms.