My daughter, 22, has periodic weakness, lightheadedness, nausea, vomiting, hot flashes. We cannot find anything wrong. It has become incapacitating. She s had regular check-ups and found no problem. Possible diagnosis has been anxiety but she is not sad or depressed or worrying about things. She is so frustrated about it and wants to be done with it! She has also had several ovarian cysts in the past. Not sure if there is a connection.