Yowie! I agree with the concussion possibility, especially if you are suddenly feeling tired, cross-eyed or the pain just won't go away with a few Tylenols and a cold pack. Have someone keep an eye on you tonight and try to wake you up every few hours and check for even pupil response. Dim the lights then shine a light into your eyes to make sure the pupils get smaller, then larger when the light goes off. If any of this happens, get to urgent care ASAP.
The swelling on the outside may be doing it's job of keeping the swelling on the inside of your skull down. You are also probably going to have a nice black eye or two in a few days.
I put my head through a windshield once.