Filling received one month ago still very sensitive and painful.

Hi there, Over four weeks ago, I received composite fillings in about 16 teeth. I just got out of braces about two months ago, am in a vacuum formed retainer (no issues until now), and decided to get some fillings replaced and address some new areas of decay. Nearly all of the fillings I've received are around the gum line. (My teeth were misaligned for many years, causing gum recession and exposure of tooth areas with thinner enamel.) Even considering the number of fillings I received, a couple of which were pretty deep, I had very little sensitivity or irritation following the procedure - except in one tooth! This tooth is directly behind one of my upper canines. The first week after the filling I experienced sensitivity to hot, cold, sugar, air, and pressure that increased throughout the week. The sensitivity from each exposure lasted longer and longer until my tooth was throbbing constantly for hours, with pain reaching up through the nerve, into the gum, and into my face. No visible swelling, though. Ice and Aleve helped the pain and throbbing. I saw the dentist one week after my original procedure. He took a quick look at the tooth and told me that this was "weird" since the filling wasn't that deep in this tooth and the tooth was otherwise unremarkable. He painted all surfaces of the tooth with a fluoride varnish and sent me on my way. It didn't help. It is now almost a month post-procedure. The issue has not gotten worse, but it has gotten only slightly better over this time - I'd say I'm at 80% of the sensitivity/pain levels that I was a month ago. Also, a new problem has arisen. Keeping in mind that I wear m retainer absolutely every night, I've noticed that it doesn't seem to fit as well and some of my teeth feel as though they are moving very slightly every day (it's like less extreme version of the sensation I got when I had braces). I am aware that the inside of the tooth and the nerve can be very excited when getting a filling - sometimes too much so resulting in the death of the tooth. However, I did not think this was likely if the decay (and filling) were not close to the root, which my dentist said they were not in this particular tooth. I also am aware that a filling can be "high" causing pain and sensitivity, but the filling I received in this tooth was along the gumline. I know that placing a composite filling is a multi-step procedure, involving drilling out traces of decay or old fillings, layering various materials in the hole, and then curing those materials. I'm wondering if something might have gone wrong with the process for this tooth and, if so, this could cause the same symptoms I'm having. If this is the case, is there any remedy? Also, I think that the final shape of the composite fillings might have changed the shape of my teeth enough that my retainer no longer fits quite right, resulting in the the movement-feelings I'm getting. I can't imagine it would be easy for the dentist to rectify this, especially since the movement-sensation is coming from a number of teeth. I hate to think it, but maybe I need to get a whole new retainer! I'd appreciate any thoughts you might have. Of course, I am going back to my dentist to tell him what I've written here. Since he didn't give me any kind of contingency plan at my last appointment (i.e. if this varnish doesn't work we can try this or that) and referred to this situation as "weird", I'm not very confident that he can help me. If not, I'll have to see someone else, since this is obviously intolerable. Thoughts?