Ugh, abscesses teeth are awful! I assume they gave you an antibiotic, too? Do take the painkillers, you need them the first few days! One thing that has happened to me is, the swelling can push the tooth up and change your bite, causing more pressure on the infected tooth. Ouch!

If its swelling from bruising, cold compresses can help. But definitely go to the ER if it continues. Dental abscesses can cause terrible infections for your whole body. I hope you are feeling better soon! Dental pain is so hard to deal with.