My crown tooth is loose, any options?

35 years ago I had a root canal (tooth #12) fail after placement of a post and crown and had a subsequent apisectomy that was successful. 6 months ago, tooth #17 was filed to level high spots. This changed my bite, and tooth #12 shifted, loosening from the gum. There was quite a bit of bleeding at the time. My dentist said it's OK. I get a bad taste in my mouth suggesting to me that this is not a healthy situation. I'm getting a second opinion, but I'd like to have some idea of possible options. Thanks.