Disappearing positive...

I took an HCG test and there was a faint line within the timeframe. I left the room to get my phone so I could take a picture to send my husband, and when I came back the line was gone...

I'm technically only 4-5dpo but we BD-ed a few days before and the day of. ( BD on 20, got a positive opk 22-24, BD 25) I know it's still probably too early to even get a positive. But I had some weird CM for the last 2 days. Along with tingling breasts. So I figured, "why not, it'll probably be nothing anyway" and then this happened...

Has this happened to anyone else and then they were actually pregnant?

I feel like a fool for even posting this. Hence the Ananymous post.