Ouch!
Seems to going around lately.
Looking around online, I found a few things, but not much. Mostly diver Web sites seem to have something to say about it.
The themes seem to suggest washing the area well, then applying vinegar, then an ointment like hydrocortisone cream.
A couple said try running hot water over it for quite a while then applying an ointment.
I found only one that had much detail:
treat the rash as you would a second-degree (blistering) burn, by keeping the affected area clean, applying a thin application of non-sensitizing topical antiseptic ointment such as mupirocin (Bactroban), and observing for the onset of infection. If the rash becomes incapacitating because of pain or itching, you might want to ask a physician to examine you and determine whether a hypersensitivity (allergic) reaction exists.<hr></blockquote>
If I were you I would dig around online to find confirmation of this or anything better. Try some of it and if it persists, seek professional attention.