I am an active healthy  female, 76 years old, though overweight. I ate a bowl of mashed potatoes about 6
Welcome to Chat Doctor. It looks to be skeletal muscular pain due to improper posture. Pain of appendicitis is on right side. This type of pain is also seen in the renal stone. Start NSAID with muscle relaxant, apply NSAID gel locally. It will subside within 2 to 3 days. Otherwise, go for USG abdomen and urinalysis, x-ray lumber to confirm the diagnosis. Get examined by your family physician for proper diagnosis and medical management.