I agree with spade take another pregnancy in a week or so or call your doctor! Brown blood is old blood, but then getting bright red blood isn't normal.
I hope it works out for you!
Typically, only half of women who bleed while pregnant have a good income - bleeding is not normal during pregnancy especially if it is bright red, heavy, accompanied by clots/cramping. Spotting, on the other hand is usually more benign.
Its possible that you are experiencing a chemical pregnancy. Its also possible that you are pregnant but red bleeding (heavy?) doesnt sound like a good sign. You could either go to the doctor for a blood test or take another HPT in a week or so.
best of luck to you.