23 Male, microcytic.

On 11/11/2025 I had blood tests done prescribed by my family doctor because I was experiencing problems with lack of strength/general asthenia. The tests showed that I have a serious vitamin D deficiency; specifically, my levels are at 10 ng/mL. The tests also showed slightly elevated levels of albumin (69%) and Folic Acid (31.1 ng/mL), but according to my doctor, these are not cause for alarm.

I want to point out that in the spring of this year, for the first time in my life, I set myself the goal of walking 10,000 steps a day, and I did so every day before lunch (between 12:30 and 1:30 p.m.). In fact, during this period, I exposed myself to the sun for about 40 minutes every day, and I have never felt so good in my entire life. I was able to study without any problems, and I also trained four times a week for two and a half hours. I started having these occasional weakness issues during the summer, when I must admit that I didn't expose myself to the sun much because I suffer a lot from the heat (I live in Italy). So I really think my problem is related to low vitamin D levels, and I would like to feel like I did during that period again.

Since I didn't feel comfortable with this doctor, I stopped seeing him and a doctor friend of mine recommended me to take 8000 I.U. of vitamin D daily.

I started to take the vitamin D approximately 5 days after the tests, let's say I started the 11/16/2025.

The first two weeks I took some simple vitamin D (two 4000 IU tablets) and then, for another two weeks, I started taking a Vitamin D3 + K2 supplement purchased from Prozis, as my doctor friend had advised me to also take vitamin K2 to help transport calcium to the bones. Each capsule of this supplement contains 100 μg of vitamin K and 2000 IU of vitamin D3, so I took 4 capsules.

About two weeks after 11/16/2025, when I started the supplement, I began to feel more intense muscle pain than usual during my gym workouts and a more pronounced sense of fatigue all day along. So I decided, on my own, to reduce my Vitamin D3 supplementation. Recently, I have continued to take Vitamin D3 + K2 supplements, but the dose varies from 1 to 2 capsules (2000-4000 IU).

Essentially, what I noticed was that:

• If I take 8000 IU a day, after 2-3 days the muscle pain and fatigue return at the gym
• If I take 2000 IU per day for a week, I feel pretty good (although not like in the spring), but if I forget to take the supplement one day, after 2-3 days I experience episodes of severe muscle weakness, which prevent me from studying or doing other daily activities.

This month I changed my family doctor and explained this situation to her. She prescribed me a 50,000 IU vitamin D supplement to take once every two weeks. But I'm afraid that taking such a large dose all at once will cause the same problems I have when I take an 8,000 IU dose, if not worse.

So I would like to know, in your opinion, what is the daily dose of vitamin D I should take, and whether muscle pain and general fatigue can actually be linked to vitamin D3 or vitamin K2 supplementation, or to an increase in calcium in the muscles.

P.S. My calcium levels in blood are 9.9 mg/dL.