Hi. Thanks for the query.. It looks like either it is a lymph node that is infected or the same area contains submandibular salivary gland that might also be infected leading to swelling and soreness in that area.. At times infected lymph nodes can take longer to resolve once the infection subsides.. You should get it checked as soon as possible as if it is left untreated then swelling and soreness can exaggerate and become painful to you.. An x Ray or ultrasound of the area can help in diagnosis.. As of now take anti inflammatory painkillers like Ibuprofen and do cool compresses over the swelling.. If infection is ruled out you can be advised antibiotics.. Hope this helps.. Regards..