Day 10 missed period/neg. pregnancy

I’m now on day 15 of having a missed period. I put in a cup because I was out all day and felt mild cramps in the morning. I just came home and took it out to find whitish discharge with tiny chunks of brown/reddish blood. I wiped again and found clear discharge with red/brown streaks as well. Is there something wrong w me? I did and still do have symptoms of nausea, mild headaches, & mild cramps.I took a pregnancy test at day 10 which showed negative :( . Wondering if I should get checked out. Help~