I just get stung by a big black caterpillar...anything to worry around?

Except for the fact that it HURTS!!!!!
Answer:

no its nothin to worry give or take a few except for the fact that if you travel to bed and wrap yourself in blankets too tight you might stir up the next morning next to wings and antennas

Appendix?!?

and itchy as very well isnt it?

Woke up with a headache that I have last dark?

Caterpillars generally don't enjoy stingers... You might have snagged a bristly hackle or something, though. Just wash the spot and use something close to neosporin if you have it.

Tonsillectomy on wednesday?

I would suggest you want medical attention as soon as possible...put ice on the nouns to keep it localized. My mother be stung years ago (but by a furry white asp) and ended up contained by the hospital for several days...She was rather ill and could not maintain any food down.