Jellyfish sting on Hilton Head Island, South Carolina, USA

I was throwing a frisbee around with my family in the water, when suddenly a sharp pain and stinging occurred on my right leg near my knee, it had to have been a jellyfish according to the beach patrol, who spray a vinegar solution on it. I'm not sure if there were others or just the one, but it was extremely painful for the first 10 minutes or so, and the pain subsided after the solution was sprayed and only stung slightly on and off for a long time after. I'm not sure if any of this information helps... but hopefully it does!