This was my experience: I felt sick after living in Seattle for about 2 years. Went to a few clinics / then primary care and was told essentially that it was in my head: couldn't find any medical causes said it may be anxiety. I actually started to believe them even though I've never had any sort of tendency to question my own health and have always been a markedly relaxed person even in stressful situations. I dropped it, but eventually, I got a UTI (unrelated) and went to zoomcare for that. They asked about my medical history and based on it they recommended the screening. It turned out my levels were extremely low even though I was already taking 1400 IU of Vitamin D a day on my own as a preventive measure after moving here. A dose of antibiotics and 50000 IU a week + 4000 IU a day for a few months and both problems are now resolved.

Anecdotally, I live in Seattle and my GP has always done a Vitamin D test as part of my standard physical exactly because it's such a common problem up here.

Weird, maybe the symptoms made it more obvious to our doctor that we had a D deficiency.