was the lotion old?
did you sweat?
did you make sure you used sunblock sport?
did you reapply every 2 hours or sooner if you sweat?
you should read up on it....i mean i feel sorry for you, cause those burns sound vicious, but you have to educate yourself.http://healthgate.partners.org/browsing/browseContent.asp?fileName=13823.xml&title=Play%20it%20safe%20in%20the%20sun
check out that link for next time...i'de hate to have you missing out on somthing you enjoy!
take care of them blisters and get to feeling better.