Check out EWG's information on Sunscreen:
http://www.ewg.org/whichsunscreensarebest/2009report
I myself don't use sunscreen - even though I am a Caucasian woman, because I myself have allergic reactions. However, they usually disappear in 2 - 3 days. My allergic reactions include the hardening of the skin, severe itching. It's now at the point where a lot of sunscreens, just the smell of them makes me nauseated. I try to be wise now with the sun - I don't go into it until after 2:00 pm, and then only for a couple of hours.
You may want to try a little tester of other brands on a little spot on your arm before putting it on completely, next time. Some brands I'm not allergic to, but I've just decided with all of the naturopathic information about sunscreens, and all of the chemicals they put in those, I'm better off eating a lot of fruit, putting Vitamin E on my skin afterwards and being careful not to burn.
The other thing I do, is if anything suspicious is on my skin, I go to the dermatologist and have it burned off immediately, with a special Q-tip and dry ice. It's relatively painless, and better safe than sorry. I've burned off itchy spots and spots that don't seem to completely heal.