Black tarry blood first day of cycle? Advise please!

Hey Ladies, yesterday I had started my cycle, and my blood was black and tarry. I've been having LOTS of cramping, and a fever of 100 on up. I've felt really sick to my stomach as well. This has never happened to me before. I know you get brown/black blood at the end of the cycle, but this time I'm only bleeding black. Anyone have an idea as to what's going on? I called and spoke to an on call obgyn (he's new to his job) and just said he doesn't think anything is wrong. Which I've talked to him before and he always says nothing is wrong when the next day I see my obgyn and he discovers something wrong. So any advise would be great. Please and thank you.