Huge laceration ! Help?

My boyfriend destroyed his thigh when he fell on some glass. He went and got it stiched up pretty good but the wound slit his muscle and everytime he move his leg it causes him huge discomfort. He takes tylenol for the pain but what should he do? Leave the leg completley still ir try to move it as much as possible? Also when cleaning it, should i apply soap directly on the wounds? and are there any natural ways to ease the pain from the wound? By the way it is a really bad cut.