oh i'm so confused

sorry but this is probably TMI

yesterday afternoon went to the loo and when i wiped saw the tiniest brown smudge. wiped again and same thing, so i thought oh ok AF is here. but then i kept going back to check every 20 mins or so and nothing....

again this morning, nothing, no AF

I POAS again this morn and still the second line is very very faint, maybe a micromicro tinge darker than the other day

this whole thing is doing my head in. am supposed to be going on a holiday this weekend (have to fly) and now am stressing about all this- what IF i was preg and went and something happened etc etc

any advice from you girls as to what could be going on with me?