If you are sewing 6 or 7 hours a day, that could be the culprit. No matter how ergonomically correct your tables/sewing machines/ironing boards are, you can only do one thing for a certain amount of time especially as you get older. My chiropractor suggests getting up and moving around as in walking up and down the hall a few times every 1/2 hour at least. I've found that helps me more than anything else. If I spend too much time in any one position, it can get uncomfortable and lead to problems. Just keep moving.