severe pain and swelling after novocaine

[lea419]

I had large cavity filled, the tooth prepped for a crown, along with a temporary put on last Friday.  That evening I was in serious pain, unlike any dental pain I've ever experienced. I've had several other crowns, but nothing like this! My cheek and gums swelled, and extreme throbbing pain below the tooth in the gum line.  The pain and swelling have continued for the past 5 days.  I went back to see my dentist on Monday.  He asked if the hurt when I tapped on or bit down on my tooth and it doesn't, the pain is below.  He thought that maybe it was a piece of cement or particle from the impressions for the crown.  He dug around in there for a while and found nothing.  He put me on an antibiotic and asked me to come back in 2 more days.  He didn't seem to know what was causing this. The pain for the next few hours afterwards was unbearable.  The pain and swelling are as bad as ever, now 4 days later.  Any idea what could be causing this?  Could it be a reaction to the novocaine?