HELP! My boyfriend has a huge hole in one of his teeth.?

My 17-year-old boyfriend has a huge hole in one of his back teeth. It bleeds a lot, and it is causing his breath to have an odd scent. He takes good care of his teeth, and he was supposed to have a root canal done last year, but the dentist office never called him back. He also has been having bad chest pain starting at his heart, which includes pain shooting down his left arm. My mother tells me that this could be from the tooth, and she also says that she knows a kid who had kidney failure due to an unfixed tooth. The kid apparently had to have a kidney transplant or something like that. I am utterly worried for him [my boyfriend], and I know you may say he is irresponsible, but he and I are going to call a dentist ASAP. Possibly a different dental office than the one he had gone to before. Is his tooth going to cause him any health problems? Is it why he is having chest pain? Please help!