Bleeding at week 6

I'm at week 6 now and discovered bloody discharge yesterday. It was brown and the amount was quite a fair bit, like half a pantyliner's surface worth. This morning, when I wiped, the discharge has now turned reddish. It's not super heavy as if it's flowing endlessly but there's a drop on the pantyliner apart from the amount when wiping and it's quite worrying. Don't know if it's a psychological reaction but I'm also getting a bad headache and feeling slight discomfort/cramp at my abdominal area. Researching a lot abt it and understand there's a possibility that it's implantation bleeding etc, but not very convinced that that is the cause because the timing doesn't really match my regular period cycle. Anyone able to share their experience on how much bleeding is considered normal/spotting and how much would be a cause for concern? Thank you very much ;(