can a blood PT be too early!!!

Monkey🐵
I've been feeling sick for almost 2 weeks nauseas, heartburns and dizziness on Tuesday because I got really dizzy and had to run to vomit  minutes later I took a blood pregnancy test which it was negative (I work in a clinic) so every single day I've been nauseas and heartburns. Today I decided to go to my primary doctor to see what he can prescribe for my symptoms and what he suggest is to get stool samples and  blood work done and of course another pregnancy test done because apparently it was too soon if I am pregnant my HCG were not height to detect "really"!! Like how is that possible if it's blood... now  back to where I started ugh