Black puke, chills, fast heart beat...help!?!?

So this is not quite as serious as the header states...i hope. I just wanted to get some attention. The past few weeks I have been getting chills on and off but no fever though. I have been waking up about 3 times a week with a really fast and hard heart beat. I puked up just a little bit off black stuff so I was not that worried. My friend said that her doctor said that when drainage sits in your stomach for awhile it turn black. I have had NO appetite for a while which is VERY odd for me! I was watching tv when my heart started beating fast again and I feel like i am going to puke...what do you think???