I posted last night but got no responses, so I'm posting again

my period ended last Tuesday. my husband and I have been bding every other day since it ended. tonight we bd'd and a couple hours later I went pee and there's blood on my panty liner. it's a light amount but enough to frustrate me. what's going on? I don't understand! this is so frustrating! it's only been 9 days since my period ended! I'm also cramping in my lower back, a little in my lower stomach and down my legs.