First pregnancy test was positive and 1 week later it negative your period came?

There are a few possible explanations for this:

Early pregnancy loss: Early pregnancy loss, also known as a chemical pregnancy, occurs when a fertilized egg implants in the uterus but does not develop into a viable pregnancy. This can cause positive pregnancy test results followed by bleeding and a negative pregnancy test.

Ectopic pregnancy: An ectopic pregnancy occurs when a fertilized egg implants outside the uterus, typically in the fallopian tube. This can lead to positive pregnancy test results but may eventually cause bleeding and a negative pregnancy test if the ectopic pregnancy is not viable.

False positive pregnancy test: Although rare, false positive pregnancy tests can occur due to factors such as certain medications, medical conditions, or laboratory errors.

Ovarian cyst: A corpus luteum cyst can form when the corpus luteum, a small gland that develops on the ovary during ovulation, does not dissolve and remains present. Ovarian cysts can lead to elevated levels of the hormone progesterone, which can produce positive pregnancy test results, even though no pregnancy is present.