I do know someone who is severally allergic to hair dye. This person experienced severe scalp pain, swelling, eyes even swell, sores on scalp, hair falls out. This person dyed their hair twice and got the same reaction and she looked really bad. Whether this caused RSD or not in your situation I'm not sure but could be that you are still poisoned from the dye. I would do nothing but let nature bring your scalp back to normal. It could be the more you tamper with it the worse it gets, perhaps. As for RSD there are many instances where the root cause is unknown. Lets hope you've got a very bad chemical reaction instead.