Suggest Remedy For Pain And Soreness On Right Side Of Chest

I was working under a car laying down with shoulders off the ground for about five mins I felt a pain in right side of chest I thought something had fallen from car and landed on me but it hadn't felt like a metal tennis ball had hit me now the day after now feels as though it's bruised sore to touch and gets worse when moving around I have no other symptoms or any bruising I am 55 years old thank you