Heat Intolerance

I am a 43 years old woman. I use to be very active and outgoing with a healthy diet. I have been taking verapamil for 3 years,however for the past 3 years, life as I know it has changed completely. My tolerance for heat has grown and continues to grow immensely overbearing.
I feel extremely hot, light headed, dizzy, nauseated, and weak, with temperatures exceeding 70 degrees. My lips are always dry.My ears, face,knees and palm of hands can get extremely red and painful, and I do not sweat. This will last until I seek relief from a wet rag around my head, neck or wrist.The heat also affects my heart rate, which can go from 100-180.My activities have been restricted indoors and outdoors. Recently, I am unable to take warm baths because my knee would pain, and it takes a while for my body to get adjusted so I have to take cold showers. I am unable to drink hot liquids or eat hot meals or spicy foods. Test for thyroids, diabetes,menopause proved negative.
PLEASE advise, hoplessly and helplessly coping ..