Why is clear blue the only test showing positive?

So I’m not trying to get pregnant but I’m not, not trying either. The last few days I’ve been nauseous and throwing up, so I decided to take a test last night. It was the Blue dye Clearblue test and within three minutes there was a noticeable but FAINT positive. I’ve taken six clearblue test since then with the same results, I purchased them from different stores and with different pee at different times of day. However, I’ve also tested with a few. First response ones, and got a urine test done at my therapist office a few hours ago, all seemingly negative. I’ve never been pregnant before and never tested positive before so I have no idea what’s happening. Also all blue lines came up within the 10 minute window, after they dried that got streaky looking and a little bluer though…so idk if that means anything.