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.
Antibiotics will save you time, and will get rid of the pain and the infection BUT ONLY TEMPORARILY.
Some dental offices provide NEW patients with free x-rays and a free consultation with the dentist, find and ask around your local dental offices and take advantage of their promotions.
(All information provided is for the sole purpose of education and not diagnostics)
It does sound like you have an infection and the tooth may have to be removed. Your doctor may prescribe antibiotics or just refer you to your dentist since the cause of the infection is not known but appears to be related to that particular tooth and will just come back. See your dentist and ask if you can pay for whatever needs to be done over time. Take care.