I think you need to pursue what's going on with his teeth. I had an argument with our pediatric dentist about night nursing and the end result was I didn't give it up, but I brushed her teeth as best as I could though after she nursed. She nursed for 2.5 yrs, mostly at night for the last year.
You may also ask around the family. When I told my mom about DD's teeth, she said, "Oh, yeah, you had poor enamel, too, at that age" and SD has struggled with cavities, too (though some of it is her own habits). My own dentist says one of his kids has been a dental nightmare from toddlerhood. So it may also be HIS teeth, a bad genetic luck of the draw, and you have to be careful.
So the bottom line is however you got here, you should get a 2nd opinion of they are bothering him and maybe ask if there's something else going on, like generic tooth sensitivity and if there's anything you can use on a 2 yr old.