For the last two months i had my cycle i was spotting but this month i've been on my cycle for 10 days is this normal i take vitamin d3

Probably normal: wait till next cycle to see if it stays normal

Not normal: Not sure why you are having this amount of irregularity. If you mean you have had menstrual bleeding for ten days - that isn't normal. Longer than 7 days is not normal. Can consult with your gynecologist. Did not see this listed as a potential vitamin D side effect. Take care.