Based on what you have described, and on a general basis, when a
tooth develops a fistula (
Lump ) it is an infection. If you had a filling, the tooth is susceptible to decay, if the filling is fractured, or just recently started to act up, the tooth doesn't need to be extracted, it can be endoed... or Root Canaled, for it's perseverance. If you cannot afford the root canal, and crown, then you would have to extract it, save up for a bridge or an implant later on.