ihearttc In answer to your question, could lower than optimal levels of vitamin d be causing the symptoms you describe. The answer is yes. That does not mean that is definitely the cause. You may have other issues as well. However, since it could be the cause, and the remedy is so easy to pursue then to my mind it makes sense to find out if you are deficient,then put it right. If that helps - fantastic, if not then at least you have eliminated one possible reason, and in the process you will have undoubtedly helped promote your health in other areas.
Your consultant was wrong to assume that a holiday months ago will automatically mean you do not have issues with vit d. A sudden glut of vit d, say from intense sun for a fortnight, will probably lead to a big increase in the storage form of vitamin d , in the blood. That is 25 hydroxyD3, which will then slowly decline over a couple of months to about half the level initially achieved, over the next two months you level will again half, eventually settling to your long term average. It is the long term average that counts, for your long term health. Your long term average depends upon your normal lifestyle,sun,supplements and food. Now you cannot get much vit d from food. (see my earlier posts).
The other issue, is that of native vit d, ie. before it gets converted to storage form. That compound is also used by your cells, in what is called an autocrine system. If you are in a low vit d state, then your body will convert native vitamin d into storage form, as quickly as possible, reducing the amount available to the autocrine system. All cells have receptors for vit d, they need it to transcribe genes to build the products of those cells, just one example is the gene to build the protein to convert tryptophan to serotonin. If a lower than optimal amount of native vitamin d is available to those cells, then you may not make enough serotonin, as demanded of those cells by signals of other brain chemical signals. With serotonin, you feel good, without sufficient, you feel not so good. While you were in intense sunlight, your native vit d would have been high, but, the native form would quickly be converted once you were out of the sun, I.e. within a few days. A regular supply of vitamin d is required by the body to ensure the autocrine system works properly. See my other post explaining this in terms of lactation, another example of native vitamin d being used by the body.
Sorry to be so long winded about it, the upshot is, yes get a test, even if your level is 50 or more, that is measuring the storage form. That holiday complicates matters a little bit, but bearing in mind your symptoms, it probably makes sense to take a regular supplement of several thousand IU daily over many months, try and keep your measured level over 100, constantly. Also try and eat a good diet containing all the other nutrients, calcium, magnesium , protein, which helps rebuild bones etc.
Good luck
BTBH