I do long hours in front of a computer. get recurring spasm in neck and shoulders. even physio therapy hasn't helped. what should i do?

Proper ergonomics: Likely you are in need of proper ergonomics at your workstation. Here is a website that has a few tips. https://www.networkmedics.com/blog/5-tips-improve-your-ergonomics I would first ensure proper ergonomics to stop the cause of the pain. Then if need be physical therapy. Medications would be a last resort. But if you have sore muscles right now you, you could take over the counter naproxen.