I too am quite an irregular knitter. I have scoliosis which causes my right shoulder to roll forwards, but I am also VERY right handed. I knit with the yarn in my right hand, casting over the right needle. (can't do continental to save my life, although it would certainly have saved my shoulder!)
So my right shoulder was getting extremely stressed with all the actions it was performing. I finally had to prop my right elbow up and keep my right forearm very still, and ask my wrists and hands to do the work. Saved my shoulder.