Tooth getting worse on antibiotics?!

I got a normal filling procedure done on one of my lower teeth, and went back a few weeks later due to serious pain. It turns out I have an infection. So i now need a root canal on it, and the dentist gave me antibiotics to kill the infection. He said the pain should be gone within 1-2 days of being on it. I think im on my 4th day of taking it (pain slowly getting worse) but i woke up today not being able to even swallow, bc anything that touches the tooth makes it CRAZY sensitive. is this normal for some people? my appt. is on the 23rd of march -to get my root canal- bc thats the only open time, but if this pain doesn't get better i might starve haha. and btw orajel quit working on this severe of a pain.