I forgot to tell you that Adderall could really make your muscle tensions much worse resulting in more pain.
The pain is probably neuralgia resulting from compression of the nerves in the back of your head due to tense muscles.
Xanax is helping at reducing the muscle tension and ibuprofen is good at reducing inflammation.
Avoid head forward posture, take breaks often while working with a head forward posture like yard work, avoid computer overuse, buy a soft neck collar if you really have trouble with head forward posture but don't overuse it as it can cause muscles atrophy.
Tense muscles and different form of neuralgia occurring while suffering from anxiety and depression are not so uncommon but it is clear that the head forward posture is not helping.
Work on your posture a lot and I think you should get results. You can also try physical therapy, I know it helped me. I have occipital neuralgia due to compression of the c2-c3 nerves probably due to chronic muscle spasms due to chronic head forward posture but I need to see a neurologist since it's been 9 months and it's getting worse.
So I suggest you see a neurologist for a proper diagnosis as some tests can be performed.
M4