I have a friend that swears by arnica gel, but she says you gotta put it on immediately after injury... And I usually keep cycling on as long as the bike is still capable of it (I think cycling another 15 hilly miles with my knee after crashing the surly didn't help). I have some gel that's arnica and ibuprofen that I use on stuff like that.

But I don't think you'll do any damage - just go easy and stop if it hurts.