I ve been taking vitamin D3. 500 IU in my multiple vitamins, + 400 IU of Vitamin D3. I m 70, and don t go out in the sun much, and I have arthritis. We bought 1000 IU of Vitamin D3. Don t know if I can take it, I can t cut it, it s a gel. Can I take it once a week, if I don t have my multiple vitamin that day?