I found out i was pregnant on monday. i took four pregnancy tests and they all came out positive. i told my boyfriend i was pregnant yesterday. amd then afterwards we had sex. i was fine thay night. but then early on the next day i started bleeding?

You could be shedding your pregnancy. Best is to see a Ob-Gyn

If it is free flowing red blood and you have cramps, you could be losing the pregnancy. Get a blood test for HCG level and repeat the test in 2-3 days. If the level does not rise, that would support the diagnosis of non-viable pregnancy. If you have profuse bleeding, see a doctor or go to ER of a hospital.