You can go to a local dental school or contact your local dental society for a free clinic possibly. I think for California, medicaid doesn't cover dental anymore for adults so it may vary from state to state.
It sounds like you have an abscess. Go to your primary care doctor and get a prescription for the infection to at least keep it under control while you find a dentist.
In the uk you could try a dental school?? Dont know if it is simillar in the US.
Sounds like an abscess - which you really should have treated as worse case scenario it can cause a the bone to die - necrosis or could cause blood poisoning...as well as a lot of pain!!