Clomid HELP has this happened before what’s going on 😫

So I’ve had positive pregnancy tests but today I took a FRER and it was so much lighter then yesterday I started experiencing cramping and VERY light bleeding like not even pink it was brown but the cramping was kind of bad so I went to the ER and they tested my blood results it was negative, I would only be 3-4 weeks so I go home sad thinking I miscarried but my cramps went away and I’m still discharging brown and it’s very light nothing like a miscarriage but my blood results came back negative after I’ve had positive pregnancy tests what is going on?