What Causes Thumping Heart Beats During Nights?

57 yrs old great health female, single, divorced. Very fit & health consciouse. Do not drink or smoke. Currently have no health insurance (working on it) as a consultant. Been experiencing bad thumping, heating beating every night from 7 pm until next morning. Sometimes it starts earlier and never stops. Gets worse around 11 pm so unable to sleep as so loud. When I do manage to get a little sleep, it wakes me up with same thing at 4 am and cannot get back to sleep. It also happens during the day. I have no anxiety, and min stress, and highly allergic to medications. Was taking 5mg claritin but too strong. I also have bad ear infections, but unalble to take steriods or antibodicts. This has been ongoing for a year and getting worse and happening every day now. I have gone thru menopause at 53, but possibly still part of it. The only thing I can take is Childrens Benedryl 1 tsp. Sometimes it is skips beats. I suspect food allergies; however, even if I eat nothing, still does it. Worse after eating within a 2 hr period. I have low blood pressure; however high cholestrol as very genic in family. The feeling of a lot of adrenaline pumping, even if not working out. A lot of pressure in the chest as well. I tried bioidential hormones but could not tell any difference. Not taking anything now except B-Complex Sublingual Liquid once a day and the Benedryl if having an allergic reaction.