What Causes Spotting Instead Of Periods?

I am a 35 year old female. I had a tubal done 5 years ago. I have had diahrea for about 3 weeks...going about 4 times a day. I also have nausea for about a week. Last night I actually awoke from my sleep and vomited. I have regular periods but a week and a half ago when I was suppose to have my period I only spotted for 1 day. I also not sleeping at night..for the last 3 weeks.