If the sore has been there for over 2 weeks and has not heeled then it needs to be checked by a professional. I suggest finding an ENT who specializes in oral cancer. With insurance problems it may be tricky finding someone who will work with you.

By going to the ER, it probably wont help. They are there for emergencies and they wouldnt deem this as being an emergency situation. I doubt they would do a biopsy, which is what you will need to find out what the sore is. But try calling different hospitals and ask about programs they offer for charity cases. Many hospitals will offer special programs but they dont advertise these things to everyone, if you dont ask you wont find out about them.

Not all family doctors are familiar with oral cancer so Im not surprised that this spot was not investigated more thoroughly. There are all kinds of free oral cancer screenings going on all over the country during the month of April. While they wouldnt biopsy the sore they can at least check you out and maybe if you are lucky they will know of someplace that will help you even without insurance.

Oral Cancer Screening Events 2013

Good luck!!!