Positive tests, then negative?!?!

Hello guys ... I am absolutely new at this and got a few questions I hope someone can help me with. 

Wednesday night I took 4 pregnancy tests which all came back positive. I do not keep track of my period therefore all I can say is that I last had a period more than a month ago. And I am fairly regualr.Today I took another 3 pregnancy tests because I am sort of in denial... 

The first, first respone test came back positive with a very faint pink line, however 2 other tests (clear blue and a no name brand) came back negative. As the day went on my stomach started having cramps, and now I am bleeding. Can anyone help me out in understanding what is happening ? Am I pregnant or am I not ? 

Thanks for your time .