My bum cheeks feel bruised and a heavy muscular ache? 28year female. not done any strenuous excercise or anything? thankyou

It is very common...: to feel a ache or bruised sensation even though you can't identify any specific trauma. Sometimes exercising, even walking for a longer time or up or down an incline, can strain the gluteal muscles. Probably using a heating pad on the sore area will help, and it will likely resolve in just a few days. I wouldn't worry any more about it. Good luck!