Had Spotting Yesterday In My Underware And Blood Was Dark.

Had spotting yesterday in my underware and blood was dark. Nothing last night it at all today but when I pee I see some particles that look like flakes should I be concerned? I'm just over 7 weeks. I previously had ultrasound 2 weeks ago when I thought I was 6 1/2 weeks they saw sac but measured I was 5 weeks 2 days and too soon to see baby and have new appt scheduled. I'm just concerned with my symptoms have slight cramping but nothing severe