Homeopathic Arnica is awesome for any kind of shock, bumps, bruises. We have both the oral tablets and the gel in the car as well as home.
As for sleeping, if you can wake him every couple hours, great; if you can't, take him to the Dr. ASAP as he could have gotten a concussion.
Got a couple things to add. (After I sent my remark about Arnica, I saw the other replies, and thought it'd be good to clarify something and mention something else.)\
Re: sleeping: If you try waking him every couple hours and he wakes, great; if you can't wake him, then take him to the Dr. ASAP as he may have gotten a concussion.
Cranial Sacral Therapy is a highly-effective yet very gentle treatment that can be extremely helpful in recovery from tweaks due to falls, blows, etc. as well as dealing with the emotional shock and stress of the experience. CST is also great--at any time in life, but the sooner the better!--for recovering from the stress and compression of the birth process. This compression has some benefits that are lost in Caeserean births, so CST can be a great idea then too.
Originally developed by osteopaths, those now trained to practice it may be massage therapists, holistic psychotherapists and energy healers. There are different schools of thought on it, the least directive/invasive of which is BioDynamic CranioSacral.