Under my jaw is swollen and hurts when I touch it I think it's a tooth infection but it started to get swollen a month after I got fillings on my infected tooth?

See. See the a Dentist that recently treated you. You may have an infection that requires root canal treatment by an Endodontist, extraction by an Oral Surgeon, or further treatment by your Dentist. Don't delay, call now.
Oral surgeon. For best results, make sure you are evaluated and treated by a board certified oral & maxillofacial surgeon ASAP.