If can get some pain killers,that will decrease the pain.
DON’T lift heavy weights for few days.
warm compressions with a cloth will be good.
if you can get a x-ray done,that would be fine because i was thinking of rib fracture.though treatment will be almost what i have told and a little bit of more bed rest

there are otc drugs that might help… I like naproxyn sodium myself, one brand name for that is Aleve. Taken as directed it can decrease inflammation and there by ease the pain from your injury.