while mowing the lawn I caught my headgear on a large limb. Before stopping the riding mower I leaned back and put intense pressure on my abdomen muscles. I felt like I had a severe muscle cramp in the upper left or mid left rib area. When I reached up to feel the area there was a large long lump sausage size. In a matter of a few seconds the pain subsided and the lump was gone. There was some minor pain at the rib sternum area left side. I lost all the pain today after heat treatment last night. Even lifted weights this AM, no pain. Muscle Spasm?