Blood work will not show if you have oral cancer or not. Sorry but even with photos we are not able to do more than give you a guess about whats going on. The only way to get a definitive answer is thru a biopsy. Either an oral surgeon or ENT would be able to do the biopsy and get you a diagnosis. Yeast? That could be thrush.

Yes, it can take weeks from the start when you first notice the sore until you get diagnosed. Any sore in your mouth which doesnt heal within 2 or 3 weeks should be checked by a professional. First there will be the initial exam and consult in which they usually dont do the biopsy. They will want to check insurance coverage first and give you the option of having the biopsy done while put to sleep or with a local or without anything at all. It will take another week before results will come back.

Hope it turns out to be nothing serious. Good luck!