Severe hives after going to the beach

[melbidd]

Sunday evening I went to the beach and walked in the water (up to my waist), when I got out my legs were severely itchy but I just ignored it.  By the time I got to the car, there were a few hives on my legs.  About 5 minutes later, my legs were full of hives, and my knees were severely swollen (I couldn't bend them).  I took benadryl and went to bed.  In the morning they were all gone.  My question is : What could have caused this? .. I didn't eat anything new that day.  I have ezcema, but I highly doubt that was the reason.  

[levDog]

http://www.cdc.gov/hab/cyanobacteria/pdfs/facts.pdf

[levDog]

http://www.cdc.gov/hab/cyanobacteria/pdfs/facts.pdf

[melbidd]

I'm sorry, but I don't think its jellyfish stings, since where I live, there is barely any at this time.  And if there was, why would I be the only one who had stings? Out of the 3 people I was with, I was the only one with this.  
Thanks anyway.

ps. my mom told me yesterday it was probably just the cold (since it was not even 10 degres out), she has hives when she's cold.

[caregiver222]

Jellyfish. Tiny nearly invisible jellyfish in the water happily swimming about doing their thing looking for other jellyfish to find happiness with and everlasting love.

You don't have hives. You have jellyfish stings.

Sometimes the reactions are so bad you have to be hospitalized.

[Dr_Subir]

U must be allergic to some component present in those waters in which you walked.