Is it normal to have pain in a filled tooth?

Hello doctor,

I had an extraction and an implant placed for tooth ​13 about six weeks ago, and I am supposed to get a crown placed on the implant in about six more weeks. Sadly, apparently due to the change in my bite caused by having number 13 tooth, a bottom tooth broke through an old filling in the 14 tooth and cracked the tooth, and I was experiencing constant low-level pain in that tooth. My dentist drilled out the old filling and filled the tooth eight days ago, and he said I still have a crack he could see, but does not know how deep it goes. He wants to try to wait for six weeks and do the crown for the 13 implant and 14 at the same time. He said I may need a root canal for 14 or possibly extraction, and he would know more when he drills it for the crown, and he said I should contact him if the pain gets bad. I had a lot of pain for three days after he drilled and refilled the tooth, and then the pain got much better, but yesterday, day seven after he drilled and refilled, I had very intense pain, and it still hurts a lot today. Does the pain mean I need a root canal (or extraction). Or is there a good chance the tooth will still be fine with just a crown?

Also, if the crack in 14 is really deep and extraction is recommended, can I add a second crown for 14 to the implant I already had placed for 13? I have read that you definitely can put two crowns on one implant, but I was not sure if that requires the implant to be centered between the crowns. In this case, the implant would be off center, directly under the 13 crown.