Pregnancy tests dark... and then light for several days... and then darkening again?

Has anyone ever had this happen? I am convinced I had a chemical. I took a cheap pink dollar store pregnancy test yesterday and it was only slightly a passable squinted positive, this was after an extremely light FRER test, the tests kept getting lighter. today I took another cheapie pink dollar store test and the line was obviously darker than yesterday’s line.... has anyone had lines that obviously changed and believed they were having a chemical and then didn’t?

I’m not getting my hopes up, I believed I’ve lost this child... as I also (as of about three days ago) lost all pregnancy symptoms - there isn’t one to be seen and that was the day the lines started getting very light. I was just surprised by today’s.

Thank you.