I'm diagnosed w/ low vit.d. was given synergy vita-d 1000iu. after a week i started having rashes on my face & neck. could it be the vit.d causing it?

Not Vit D but...: Vitamin D is a hormone our body produces and can't possibly cause rashes. However, supplements have other ingredients. I wasn't able to find the other ingredients in Synergy Vita-D but it's possible you are reacting to one of the other things in it. It could be a coincidence but it's reasonable to try a different brand. Most adults need 4-8000 iu/day in fall/winter. See http://tinyurl.com/2chkcer