When to get core buildup filling & crown

I have right lower jaw pain under ear and neck with mild Swelling for 4 months. Been to ENT, dentist. Dentist told me to extract upper right wisdom tooth and I did that on July. He then said I have a fracture or crack in lower first molar and told me to extract or do RCT. I went to Endodontist and he couldn't see any fracture through microscope. He told me to do RCT since that tooth was very sensitive to bite on bite stick and to cold spray. I did rct 12 days back. I am in USA. Here endo will do RCT and we have to go back to general dentist to get core buildup filling and crown. I still have the same lower jaw pain under ear and side of the neck with mild swelling and small lumps. Don't know if the tooth has fracture in the root. How long can we wait to get crown after RCT? I am still having the same symptoms and wanted to see if it's because of this tooth or some jaw issue.