How long after root canal treatment before permanent seal is put in, and is it normal if it is still hurting?

Root canal treatment: Usually is accompanied by mild or low grade symptoms for only a few days. A "seal" shoul be completed very soon after. Immediate seal is best. Many teeth also need a crown after a root canal. Don't wait too long for this crown if your dentist says its needed. If you are having lingering symptoms after a root canal, call your doctor and go in for eval.

2-3 visits: Normal root canal treatment can be done in 2/3 visits depending on if tooth is badly infected or not. Usually should be followed by a crown unless the tooth has enough structure to stand with just a filling over the root canal tx. It shouldn't be a painful experience rather a little discomfort might be felt for a day or two after.

Permanent Seal?: By permanent seal, do you mean permanent build up? Permanent crown? Or permanent rc filling. If there is still pain, the root canal treatment should not be completed, and if it is completed, my opinion is that the root canal filling should be removed and either extra/accessory nerve canals looked for and cleaned, or if all has been found, the canals should be medicated till pain is gone.