Recently diagnosed with scoliosis and having very bad burning in my knee and upper left shoulder. Why?

Today was my first day of physical therapy and my therapist said to sit straight all day to help with my posture, though it is really burning/almost hurting my back to do so...and it is getting worse. Same with my knee. It has this incredibly noticeable burning sensation and it's constantly there now. My doc said to take Ibuprofen every 2 hours for the pain/inflammation and ice my knee, but neither are helping at all. I'm not sure if the burning is worse because of the physical therapy (I see my therapist again Thursday) or if it is not the scoliosis and something else. I'm not sure if I should "stick it out" or call my Doc tomorrow and tell him about the burning...again.