Is anyone else in similar shoes?

So AF was due this past Monday but last week Tuesday I started spotting and it lasted for about three days but never enough to use a pad or tampon and it was mainly when I wiped. Anyways Saturday after the spotting I was out shopping and I had to sit down because I started swaying like I was about to pass out. I've had nausea and light headidness... Back ache and when it comes to boobs... The only thing that is sensitive are my nipples... I have noticed that my heart rate when sitting down and just watching tv is extremely fast. Anyways Monday came and i was expecting to see AF but today is Thursday and there is no sign of AF. I've taken pregnancy test but they have been negative. Am I going crazy?