Why There Is Severe Pain On Tooth Followed By Root Canal?

Male, 64 years , 6 2 , 190 Had a root canal on tooth #10 on Thurs 03/28/14, No problems until Early Sat morning. Pain was severe and woke me from sleep at 2 am. Took a Vicodin 7.5 and applied Ice, after about 45 minutes pain subsided. The pain kept coming back and took another 7.5 at about 6 am same result The pain and severe tooth sensitivity continued throughout the week end it was so unbearable that I went through 1/2 of a 5 325 percocet tablet about every 3 hours sometimes taking a whole one every now and then when the pain was severe Went to back to endodondtist on Monday morning and he said all was fine and prescribed some antibiotics and 12 percocet for pain. Monday - Tuesday went okay but I noticed about 2-3 hours after eating the swelling and pain came back and also sleeping in bed. I now sleep sitting up when I can sleep Now it is Wednesday and it is happening still but with not as much frequency. The gum area above the tooth is swollen along with the side of my nose about the middle of nose. The gum is pink in color, if I touch the area around the nose inside lip I can feel the pain start to build The tooth was so sensitive that I could not touch it until Monday, the sensitivity is much better The canal was very calcified and took two hours or better to get to bottom of root with no discomfort X Ray showed very minor abscess before procedure and the root filler to the bottom of root without extending past it. Oh, he had to drill through a crown to get to canal and ended up breaking it in half Sometimes it feels as if getting better and trying to figure what sets flare up off, I eat soft foods on other side but every now and then on sat sun i hit the tooth( that was really BAD) thanks for your answer in advance