It's suggested that you don't take pregnancy tests unless it's the first morning urine. As you wait until later and later, the things you drink will dilute the urine and it won't give you an accurate test. So yes it's possible to get a negative test after a positive.
Same happened to me, I bought a dollar tree test first and right away was positive, but when I bought a more expensive brand it gave me a very very faint 2nd line. Good luck and Congrats.. ")
Yup...if you got a + then you are pregnant. Also, you may be to early in your pregnancy for the EPT to show a +. And you should use your first morning pee, sounds like you didn't with the EPT. Wait another day and retest in the morning....Good Luck...You got a +!!!