What Causes Hot Flashes And Feeling Of Discomfort After A Complete Hysterectomy?

Hi I had a complete hysterectomy with overies removed 20+ years ago. I took premarin for many years then started taking the vevelle patch about 5 years ago. My Dr. said I should try and get off the meds which I have tried and I still get such hot flashes and very uncomfortable feelings. At night in bed as well as during the day. I have been reading and they say I should have progesterone as well since I take a thyroid medicine. What do you think?