Hi Kelly. I haven't bottlefed before, but it does sound to me like there's something amiss. He does still need his milk as it is the most important thing in his diet for the first 12 months. Sounds like it could indeed be the teeth... I'd suggest you just keep persevering, but try not to react negatively if/when he refuses.
Sorry I'm not any more help. I hope things get better for you guys very soon.