I'm lost!

Ok so I lost my son in August had an erpc 9/2 at 18 weeks.

Last month I got several positive frer and walmart tests went for blood work and was told my betas were 1. Told it was possibly a chemical and i should get my cycle soon.. ok....

Got my cycle light then heavy for 3 days. Had sex after my cycle now I'm on cd 15 or 16 and I had the worst headache, pain on right side and nausea.

Said f it I got one test take it cause I'm an addict.

Lines showed up right away! How is this even possible! I know frers are really bad for indents and faint lines but this ain't a squinter.

Has anyone gotten a faulty test like this?