My right forearm is swollen and feels warm, cant use it to do much.?

feels like a rubberband being pulled when i bend wrist back or turn forearm slightly to the right. its swollen and warm. someone told me there may be fluid in there. b ut i dont remember injuring it. I own a cleaning business and have a mop that i wring out so im thinking maybe it caught up to me. any help would help. I am putting it in a sling for now