Tremors, Hot And Cold Sweats, Numbness Of Extremities, Lower Back Pain. Any Suggestions?

l have had severe tremors at night and sometimes during the day.hot cold sweats and numbness of extremities,lower back pain this has been happening over the past year and is getting worse, have had various tests,bloods, mri and all testa are coming back negative am a 70 year old man who has always been very active and fit have had prostrate cheched and this is ok, any suggestions to help relieve or nail down the cause lack of sleep is begining to tell. many thanks