People tend to get misled by warnings toxicity by high doses of some vitamins. In the case of Vitamin D, you'd really have to overdo it a lot for several months to get to toxic levels.
If you examine this deeper, you'd find that it's not very easy to do, more so when you follow a doctor's recommendation and just overdo it in an effort to enhance its effects. Take a look at the dosage of supplements, look up online on how much is toxic, and the answer will change your mind on unfounded fears such as this.
I'm purposely not giving details in this comment so that people are free to lookup different (scientific) sources and decide.
If you examine this deeper, you'd find that it's not very easy to do, more so when you follow a doctor's recommendation and just overdo it in an effort to enhance its effects. Take a look at the dosage of supplements, look up online on how much is toxic, and the answer will change your mind on unfounded fears such as this.
I'm purposely not giving details in this comment so that people are free to lookup different (scientific) sources and decide.