There’s a great article over on the Lemon Tree Tales’ web site, Sewing Room Ergonomics or why does it hurt when I sew?.
My sewing machine and table set-up are my problem. I really need to lower my machine, about 4 inches, but can’t afford to buy a new table right now. I can raise the chair, and will try that again, with the presser foot on some boxes. I found the presser foot kept falling off the phone book I was using in the past. I only feel the stress when I’m doing the quilting part, no problems with piecing or regular sewing.