Bad toothache please help?

I have a horrible toothace and this tooth has been bothering me for a lonnng time. I went to the dentist a month or so ago, and he gace me a root c, and now the same tooth hurts again. My real dentist was sick at the time and they let a temp do my tooth, i had 1 root c(both with temp dentist) and when i went back to finish the 2nd one the temp dentist forgot what he was supposed to do and almost gave me a crown. It seems like my teeth have gotten worse since i saw that dumb temp dentist. can i sue him, because now the tooth he supposedly fixed that cost like $500 now is in the worst pain ive ever experienced. what do i do? i dont have money to go to a different dentist but im scared to go to my same one.