White vinegar only neutralizes the nematocysts (coral stingers) venom, preventing them from firing more venom into you. I doubt it would help you now. You have probably showered which would have activated all the stingers that were on you.
See a doctor and I'm sure you'll be prescribed an ointment.
For future reference:
Once you get stung you should notice it. The only solution then is to treat with white vinegar to stop unfired stingers from firing, and then either take a towel or sand and rub if on you to remove any stingers that are still on your skin. Nematocysts can lay dormant on your skin and not fire till much later. I don't know what stimulates them to fire later on, besides fresh water.
Washing yourself in fresh water will cause the nematocysts to fire, so if they're on your skin you'll feel it. I would advise to wash all your neoprene in fresh water after you exit and before you take any of it off. Make sure none of the fresh water gets on your skin, this will fire all the nematocyst stingers and prevent them from rubbing off and sticking to your skin in the future. As for your exposed skin you can wipe yourself with a towel to scratch off any remaining stingers. A little white vinegar will increase your chances that none fire when you're rubbing, but for me personally I've never used it. Be sure to keep any vinegar away from your eyes.
Of course nothing beats prevention in the first place. Don't touch the coral and don't poke the jellyfish.
Source
Lifeguard training for jellyfish stings (Jelly fish also sting with nematocysts)
And by the way, pee usually has more freshwater than urea, so don't pee on your stings