I have never been low in vitamin D but lately dealing with this parasite problem in my home and in my body I noticed my vitamin D level is horribly low. I did the same thing and started 5000 Iu vitamin D with Kp that I got on Amazon in a dropper bottle and it certainly does make a difference. So apparently the parasites lower your immune system. So good to see people doing their own research also because my doctor thinks I need mental health even with pictures of what's in/on my body!