Brown discharge TTC

Okay so I feel like a broken record asking all these questions all the time. But my period isn’t due until tomorrow, I tested positive for HCG 8DPO and went to the doctor and she gave me a qualitative blood test and a urine test and both came back positive. Today I noticed brown discharge followed with cramps. I’m really worried I’m going to get my period tomorrow. Anyone know if it could be implantation bleeding even though I already got a positive or was it just a chemical pregnancy and i should expect AF tomorrow