Hello. I Am A 75-year Old Woman In Good Health.

Hello. I am a 75-year old woman in good health. For the past six months or so, I have experienced a painless spasm on my left side only (waistline). I don't have it every day and sometimes I forget about it. When it does happen, it almost feels like a baby kicking (without the pain), but at my age, I know that the latter can't be true. It happens when I'm sitting or lying in bed, and sometimes it is so strong, it startles me. Thanks for your time. It's a puzzlement. - Wendy