My husband was helping me stretch by pushing my leg over my head so that it touched the floor while I laid on my back. I suddenly got an intense cramp at the bottom on my rib cage, towards my right, in where I would guess my diaphragm was. Breathing felt strange and there was somewhat of a tightness. I immediately told my husband to let me put my leg down, and the intense cramp went away. The tightness stayed for a minute or so and then went away as well. The area is still sore though when I sit up. What happened/is happening?!