Oof you sound like me, although I'm getting better. I was also diagnosed with a bit of mygalia although the Rheumatologist didn't want to stick me in a definitive category.
Sitting in the same position for hours upon days, being stressed, well it did make me very tight. My breathing was off, my posture was off. Without being aware that every time I did get stressed, I would tighten up certain areas. Even now that I've worked on stopping this for the last couple of years, I will sometimes just automatically tighten up out of habit. I had to move around away from the desk every 20 minutes. When I'm even cooking I have to make sure I'm doing deep breathing and not tightening up.
You know how you can see some people tighten their jaw, either when they get stressed or are concentrating. You could be doing that with other muscles in your body. Basically even though you are in a new job and the stress has lessened, you might have to retrain yourself out of any habits, first you need to become aware of these. This might just be one of the many things you have to do, its hard to say really.
I'm trying out some magnesium, vitD and extra fish oil, along with a hot shower and some deep breathing exercises before bed. I'm not sure if its helping during the day, but I've been sleeping more relaxed this last year.