Severe cramps 8 days after heavy period

My period was due April 29th. On this day. I had cramps so I thought my period was coming. Then, the next day I noticed a yellow discharge and I immediately thought I was pregnant because it’s the exact same discharge I had with my two year old son and my six month old, but I said I wasn’t going to over react. The first of March my period came down extremely heavy. I was soaking through an over night pad and through my sweat pants not once but twice. I thought it was just heavier than normal period and in a few days it would be over... eight days later I’m still bleeding granted now it’s brown but I’m still bleeding and my period is usually 5 days. I’m cramping to the point I can’t even sit up so I told myself if the pain worsen I’ll go to the hospital. I took a test but it appears negative. I think I see a second line but I’m not sure... is this a miscarriage? I’m not sure...