I Have Excessive Sweating. Usually All Night And When I

I have excessive sweating. Usually all night and when I exert myself in the smallest of ways. I'm like an oven. After it passes I may go into chills a d not be able to get warm. I'm 67 a d this has been going on four 4 years. My doctors aren't helpful. I also feel so weak after exertion and the sweats and ha e to lie down. It isn't my heart. I've just been through several tests. It isn't my lungs. I do have asthma.