Am I Having Miscarriage?

I am 6 months pp and exclusively breastfeeding. I had What I seemed like a miscarriage at 7 weeks pp I had a very faint line on a pregnancy test and then bleed like a period a cpl days later, no period since. I am now 6 months pp and I have another very faint line on a test and I have been having very dark Red and brown spotting for about 3 days, any idea what s going on,am I pregnant and this is implantation bleeding, the start of a miscarriage or What?