Coal tar shampoo/Neutrogena T-Gel when pregnant?

I am 8 1/2 weeks along and have been getting flaky scalp! Last week, I used a very small amount of the Neutrogena T-gel shampoo without thinking about it, and now I'm worried that I shouldn't have used it! I've been seeing things on the internet and making myself scared. I obviously won't use it again, but do I have anything to be really concerned about? Has anyone used it or talked to your Dr. about it?Coal tar shampoo/Neutrogena T-Gel when pregnant?
I have talked to my regular doc and ob gyn. They both say it is a class C. That means it has not been tested on humans due to possible problems in rats/ mice. They both said do not use it. Supposedly apple cider vinegar is a natural safe remedy. Sometimes I just put globs of lotion on my head at night and wash hair good in the morning if it gets really bad. No, do not worry right now. Using something one time will not do damage. It would be a possible problem if you used it on a regular basis. You are fine.