hoplittlebunny Yes, if you have been getting sun exposure as you described, over a few months, then it would be expected that your blood level of 25hydroxyD3, would be higher.
it is UVB in sunlight which makes vit d in the skin. UVB. Is only present in summer months 10 til 3 pm, in the UK. in April and Oct , only around 1 pm, for about an hour. Also.sunlight should be direct, not through windows, or clouds, which will absorb some uvb. Suncream will stop you making vit d, especially factor 15 or above. To get a good vit d response, try to expose 40% of your skin at least. Are you at a high latitude, Scotland, ? Light there is particularly weak, specially West coast. The closer to solar noon, the more uvb is present. Solar noon in the UK, is. 1pm. BST. Be careful not to burn yourself, little and often is best.
If you have been treated for 3 weeks, then not much time has elapsed, to allow vvit d to work. Normally with bone problems , it would take months. If you need to rebuild bones, then try and get bone nutrients in your diet. Calcium, magnesium, etc. Bone is 50% protein, make sure you get at least 1.2 gr per day per kilo of body weight.,
Is your prescription. D3, most vit d researchers would recommend that rather than D2 form.
It would not be unreasonable to have a daily D3 dose, however you are under the care of your medical professionals, and you should consult them about your intentions.
If your blood level is 25 now, then it is likely that you will need to carry on taking some vit d after your loading doses have finished. Possibly 3000 or so per day. Check you blood level, make sure they are going in the right direction. Allow time for it to work.
Of course you may have other issues which are causing your problems, as well. By making sure you have a good level of vit d , you are giving yourself a fighting chance !
Good luck
BTBH