i need some advice please.

i had a missed miscarriage in june 2023 and got pregnant again november 2023 and had my baby july 2024. he is now 3.5 months old. my period is 6 days late and i have brown discharge. going through my first miscarriage i had the same sort of thing. i did pregnancy tests but just crappy ones (not clear blue) and they are all negative. is there any other reason why i would be having brown discharge? implantation bleeding? miscarriage? ps- this pregnancy was not planned. i took a morning after pill 3 weeks ago after unprotected sex