I Am 88 Years Old. I Try To Stay Active

I am 88 years old. I try to stay active by volunteering. But lately, I am extremely tired, cannot keep my eyes open, my legs are swollen. I believe I have arthritis in my hands. I have no appetite and I hate feeling this way. I am taking amlodipine and hctz for hypertension and Zocor for high cholesterol. I eat plainly, mostly vegetables and bread - no salt very little meat. Do you know why I feel this way.