CLKD, I too get a bit of stomach upset from Vitamin D. I use the drops. I take it for a few days and then notice my stomach is feeling tight, so I stop taking it for a few days. My levels were low-normal last time I was tested, so I'm not that worried about taking it consistently.
My mother, who is 78 and spends most of her time outside in the summer, still had low D levels when tested. She now takes a pill every day. As we age, we lose our ability to turn the sun's rays into vitamin d in the body or something like that.