<s>[INST] I have had pain near maxillary 2nd molar on left side.  Xray showed a large circular space, like an abcess superimposed over the sinus.  I have been in bad pain, taking advil 5 times a day.  I had o go to soft diet and had horrible headache, TMJ soreness, pain if I touched my max sinus.  I wanted the tooth out, since I had a previous rootcanal and crown.  I am a dental hygienist.  Today the pain is gone with the tooth and I ate more and no advil for 6 hours.  The sinus is sore to touch and TMJ still has limited opening.  I use a cpap and my left nostril has been dripping for days.  I wonder if this is a sinus problem, not tooth.  Looks that way now.  How can you do a differiental diagnosis?Thanks,Donna T [/INST] Hello, Thanks for consulting ChatDoctorRead your query as you have pain near 2nd molar this pain can be due to infection in tooth, it can be due to carious tooth formation of periapical abscess or due to infection at apex of root causing inflammation of floor of maxillary sinus. For this I will suggest you to consult oral surgeon and go for investigation Iowa X-ray or waters view radiograph for examination of sinus. Hope this will help you. </s>