Molar Pain

She is a little young for it to be her 3rd molars, but its not unheard of for them to be coming in at 13. It is more likely that she is late getting her second molars (the ones in front of the wisdom teeth). If she has a small jaw, they could be impacting. I assume the dentist would have taken x rays?
Do you have a dental hygiene school near you? I am in dental hygiene school right now, and for $15 we take full mouth x rays and panoramics, as well as give you a full oral check and teeth clean. Its hard to say without x rays, but it doesnt sound like your dentist really cares about his patient if he is willing to leave her in immense pain.

Has she tried taking an OTC pain reliever such as ibuprofen or even acetaminophen?

A tooth growing in behind what? If she has an adult tooth trying to come in before losing the baby tooth, then that tooth will "grow in behind" but it's not something to just dismiss out of hand. It can be very painful and it can also cause her all sorts of problems with her adult teeth.

I would take her to another dentist. Seems to me that the baby tooth might need to be extracted.

I feel her pain. My wisdom molars all came in at once, of course i was 21. I took ibforin, chewed on straws, ice cream/popsicles.

Maybe you should see another dentist for a second oppinion (she could have infections. cavities or other) or a recommendation for a specialized dentist. When i had my wisdom teeth pulled, they came me some pain meds and i am thinking that might help your daughter sleep at nite.

Another thought I have is does your daughter have bad allergies? When sinus get inflammed from allergies it pushes pressure on my ears, nose, jaw, teeth, eyes, headaches, and etc. I had to do allergy shots to help with pain.

I have had a few absesses in my molars and those hurt too. The best OTC pain med that I used was Advil (Ibuprofen).