18 month old has had fever ranging from 100 to 102 degrees for 32 hours now. Have been giving Tylenol and has been responding to that. The temp lowers then 4 to 5 hours goes back up. Has slight diarrhea and a rash on behind. Will drink water. and eat some foods. I think its teeth. How long should we ride it out for before going to Dr. Office. Also about 28 hours into this the fever went away and he was acting as normal, then 3 hours later back to 101