Having mass in submandibular, advised removal. Very painful, on antibiotics, enlarged lymphnodes. Suggestions?

my 15 year old daughter has a mass in here submandibular, she has had periods through out the last year and a half where it would swell. Our family daughter thought it to be a blockage gave her antibiotics. a month and a half ago it got very large and was hard unlike the other times when it was soft. we were sent to an ent and after ct scan and xrays we were told she has a mass it is either a cyst or a tumor . up til a month ago she didn t experience any discomfort but know she is in severe pain. she is schedule to have it removed in 6 days. starting 6 days ago she developed a fever over 100, and swelling and pain they put her on antibiotic which was a Friday. on Monday she still had a fever and the swelling and pain had worsened. we were told to bring her straight in to be seen. the dr examined her and said she must be grinding her teeth at night and her jaw joint was making her hurt. and she probably has a viral infection causing the fever. we really do not agree. there are now what I believe to be lymph nodes enlarged on the side of her face right on the jaw bone above the mass. they are very painful and she is still running a low grade temp. she is on 875 mg of augmentin twice a day and can only take tylonel now due to the surgery and blood thinning of advil . neither of which helped the pain anyways. she can barely talk and eat. any advise, should i take her to her ent again, i am afraid he will say thesame thing about her grinding her teeth. should we go to our family dr. or a walk in clinic or the er.