positvely not pregnant

can a female think they are pregnant and test positive on a pregnancy test but a few days later test negative?

[peekawho]

It is not possible to merely "think" yourself into a positive pregnancy test, but there are situations where a woman may test positive, and a few days later test negative.

Lots of reasons.

She may have misinterpreted the first test as positive (sometimes there are shadow liines, evaporation lines, or simply misreading the test)

She may have tested the second time and not followed the directions (tested without using a first morning urine)

She may have used two different types of tests (the first test may have been a very sensitive test, and the second test less sensitive)

She may have had what's known as a chemical pregnancy, where a pregnancy stops very, very early on.  There can be an initial slight increased level of the pregnancy hormone BHCG, which then quickly decreases when the pregnancy stops so early).