I'm a male, 41, 6" 4, 226 lbs. Recently have lost almost 40 lbs. (over a year's time) Ran really hard last night, went to bed, woke up with pain in lower right abdomen. Don't feel any nausea, loss of appetite. Have had minimal bowel movements, in fact, took an enema last night to help. Sometimes happens as I am on a low carb diet. I take fiber pills daily and try to eat lots of veggies, but still, at times, constipated. Probably just stretched a muscle and have slight constipation? I've been constipated before plenty of times and never experienced this. It's not a sharp pain, and only really feel it when I get up from sitting or lying down. Walking, it comes and goes, which leads me to believe a muscle strain.