Sunburn, Sunscreen and painful reaction

I have been trying to find an answer to my problem for several years now.  Over the past 15 years, I have had a reaction to the sun.  I am fair skinned and burn somewhat easily, however, there have been about 5 -7 times in my life when I have had a severe reaction.  It consists of severe stinging, stabbing pain that pulsates and moves to different points on my back.  Now, this occurs only when I have a sunburn.  The pain is so severe, I usually end up in the emergency room.  However, I have had sunburn before, very severe sunburn, and not experienced this reaction.  I am familiar with the pain associated with sunburn, and have had painful sunburns, however, I know that this pain is not caused by sunburn alone.  Also, the five or seven times I've had this reaction, I was using sunscreen.  I have never had it when I have not used sunscreen, but I have used sunscreen, been burned, and not had the reaction.  I thought it may be a reaction to some ingredient in some sunscreens, but I'm not sure.  I havnt used sunscreen on my back in about 4 years, and have not had the reaction.  Also, when I was young, I was burned by some chemicals placed on a lawn by chemlawn, on my back.  I don't know if it could somehow be associated.  Any help would be much appreciated.

[Accents]

Sorry, I don't have a specific answer to your condition. But I think the skin has some sort of memory.  Someone in our support group for sun sensitive people might have an idea of what your condition is about.

I have created a support group for sun sensitive people.  
Our website is at Website: http://sun1.awardspace.com/index.html
Our forum is at http://groups.yahoo.com/group/sun1/
To join, you need to join yahoo, then join our group. Please come by and say hi.

We are a support group for people who suffer from sun sensitivities such as solar urticaria, lupus, porphyria sun hives, photosensitivity, sun allergy, rheumatoid arthritis, actinic prurigo, hydroa vacciniforme, chronic actinic dermatitis, albinism, and more. We share our experiences and ways of coping and living with sun sensitivity such as sunscreens, clothing, hats, sunglasses and the effectiveness of medical treatments. Sun sensitivity shows usually shows up as a bad sunburn in a very short amount of time. Sun sensitivity can be due to drugs or medications, plants, phototoxicity, genetics and diseases.

See you there,
Accents

Moderators: We are a rare group, so we have a tough time finding each other. So I would appreciate you letting me post this message.