What Causes Cramps Between Hips And Knee During Nights?

I am 66 y.o. female, smoker. I have had cramps in my calves for many years, usually after a lot of walking. Now my upper legs between the hip and knee on the inside are cramping at night. It doesn't happen every night, only after a hard day in the yard. No swelling in lower leg or feet. I have been doing a lot of yard work, heavy lifting, walking, mowing with a walk-behind mower. I am told I don't get enough water, but I do drink a lot of water. I take multi-vitamins and extra vitamins for my eyes, prescribed by ophthalmologist. I was told by a non-medical person that these are symptoms of pre-stroke. Is this true and what should I do to prevert the pain?