I've been through this, and am nearly back to normal. Roughly in order of importance: Fix your work ergonomics, lifting & massage, and reduce stress.

The neck and joint pain stuff sounds a lot like ergonomics issues. Until it stops, work only at a desk, only with an external monitor or raised laptop screen, and only with your elbows at 90 degrees. Get an ergo keyboard that is split, such as a kinesis. Do not compromise on this until you are pain-free. Take breaks frequently.

Lifting and massage are great too. For lifting, the big compound lifts help a lot, but be sure to handle muscle imbalances so you can make progress without injury. For example, I have to do a ton of side-steps. Postural exercises are really useful too. Anything that strengthens your neck and shoulders so you can pull your head into the right position.

The tensing up is hard to avoid but very important. Therapy is a tool for dealing with this. It's helpful to realize that people tense up because, in the moment, they believe it will improve their work output, but really it doesn't.