I colored my hair with the same product that I have been using for years, 8 days after I colored my hair this time, I got very painful sores on one side of my head. I have been to a lot of doctors to try to diagnose this, they all come up with different answers, shingles, infection, lichen panus. They all said that this couldn't be an allergy to the hair color. I haven't colored my hair in 5 weeks now and I'm still getting a couple new sores on my scalp. I don't know what is going on. Could this still be a color allergy?:

If the doctors say that it's not an allergy, I'd go with that for now -- at least until you have evidence to the contrary. When you want to retouch again, do the patch test under your arm or on your leg at least a day before you color. If you get a flare-up of symptoms at the site of the patch test, you'll know that you do, indeed, have an allergy. Otherwise, no.

I agree with Perito that you should confirm whether you are allergic to hair color with a patch test. However, I don't agree that the doctors are necessarily right. I am curious about the lichen planus diagnosis. Was it confirmed with a biopsy? Even if it is lichen planus, it could be related to exposure to the chemicals in hair dye, specifically p-phenylenediamine. Google "hair color concers" and read that website for more information.