Nausea, Diarrhea. No Periods, Novasure Surgery Done. Endoscopy, Colonoscopy, Allergy Test Negative. Hormonal Imbalance?

Been dealing with light headed, nausea and mild diarrhea for about a year now. It comes and goes about every month. I have been tested for everything! Gluten allergies, other allergies, had a CT scan , ultrasound ( gallbladder ), endoscopy, colonoscopy, blood work for various things, all negative. Even thought hormone imbalance of some sort. I no longer have periods because I had the novasure surgery about 8 years ago with no complications. I believe it still may have to do with hormones but do not know what to do next. I am 45 and in good health otherwise. I did lose about 22 pounds within that year because of the loss of appetite but I am a healthy weight.