Anyone react strongly to sea lice?

Hi there, I just got back from the 5-mile St. Croix Coral Reef Swim--a terrific race for anyone considering it. I've done this 4 times, and despite what I am going to ask about, I highly recommend the race. I saw tons of turtles, rays, and had a great 5 days in the sun. Given all of that, during last year's race, I was stung by a man-of-war, and "sea lice." The man-of-war sting was extreme, and required a hospital visit as I developed a systemic reaction. (This kind of sting is almost unheard of in St. Croix so don't let it put you off the race!) This year, I seem to have been attacked by sea lice again. The last two days, in addition to the bumps and itching, I have had a headache, felt feverish, had the chills, and generally felt like I have light flu symptoms. I am also sleeping really badly. I've been up since 4, totally unable to get back to sleep. I didn't equate the other symptoms with the reaction until I did some reading. Now, I'm pretty certain they're related. Has anyone confronted this? My concern, based on looking at some things online, is that now that I've started these kind of reactions, they will continue to get worse the more times I encounter the little beasties. I hesitate to use the prednisone I have leftover from last year's man-of-war sting, but I'm feeling pretty lousy. (No pun intended!) What have you done in the past? And have you tried Safe Sea, the supposed prevention lotion? I love the sport, but I'm paying for it dearly in terms of how I feel! Thanks for any advice.