Jaw, tooth, and air in ear

I am a 29 yr old woman experiencing pain in my mid jaw, throbbing pain in between my 2 and 3 upper molar and air in my ear. I have had this on going pain for a month now. I went to the dentist last week and she said I had no cavities and it could be allergies, grinding my teeth, or brushing too hard. I though I needed a root canal. I am so confused as it could be several things.My allergies have been fine although I have taken Zyrtex to see if it helps. I am not sure if I should get a second opinion or what to do. I have taken Advil and it does not help the pain. My jaw has a light pop if I open and where the pain is. Should i get a second opinion or go to a doctor?

[SIENK1984]

You have symptoms of TMJ.   I would visit a TMJ specialist to get answers.