One solution may be to re-line the denture. This involves placing an acrylic reline material in the denture and allowing it to set in the mouth. This will allow the denture to re-conform to the mouth. The second option is to re-base the denture. This is a rebuilding of the base of the denture.It is more involved and restores the denture base and flanges to a custom fit. The third choice is to fabricate a new denture. Since you state that your denture is about five years old, it may need replacing if it is too worn or has been repaired. If you have dental insurance they may authorize that they may pay for the replacement.
The swollen gums will resolve as well. I recommend that you rinse your mouth with hot salt water. Take one tea spoon of salt in an 8 oz glass of water, as hot as you can stand it and rinse your mouth by swishing it around. The salt water pull the excess fluid out of the gum tissue and the swelling will go down. Repeat this process three to four times a day if you can for a day or so.
If you are uncomfortable, over-the-counter pain relievers such as Tylenol or Advil should help.