chemical pregnancy

i took a pregnancy test and the first one came out positive. i took four more and they were all negative. i then went to the doctor and received another test, it was negative.

after some research, i came to the conclusion that i had whats known as a chemical pregnancy/an early miscarriage but i'm not 100% sure.

"A chemical pregnancy is a term used to describe a very early miscarriage which occurs before the fifth week of gestation and well before the fetus can be visibly detected on an ultrasound."

has anyone ever had one? what was it like?

is there anything else that could've caused the first test to be positive?