Went through the same decades ago. Was prescribed Vitamin D 50,000 IU, once a week. Helped a lot. Best of luck!
Vitamin D only really has dramatic effects in people who are severely deficient. Despite all of the influencers and podcasts claiming it's a miracle supplement and that we're all deficient, actual Vitamin D studies don't show much or any benefit outside of people who are significantly deficient.
But yes, if your Vitamin D is actually low then getting it into the normal range could have some dramatic effects.
Some doctors will prescribe short courses of Vitamin D as an almost-placebo when they can't find anything else wrong. It works quite well as a placebo for many people because podcast health influencers have been talking about it so much lately.
Fat-soluble vitamins (A/D/E/K) can accumulate in your tissues over time if you keep taking too much.
Water-soluble vitamins (such as C) are much easier for your body to filter and flush via urine. You could still overdose in the short-term, but a chronic accumulation is unlikely.
Not going to go into detail but there are several recent studies showing that daily intake of up to 50k IU is safe. The concerns over hypercalcemia, etc. were tied to much larger doses per day.