Miscarriage without knowing if pregnant beforehand?

Emily

So end of May me and my boyfriend had sex, then a week later I came on my period, obviously that’s usually a sign of no pregnancy, so I just left it to be I’m not pregnant, however. This morning I bled a little bit then bled a shit ton, I can’t work out whether this is a period or a possibility of miscarriage. I had my implant out early May time, so I can’t work out what’s going on. I’m in a lot of pain but didn’t have any period symptoms before the blood started coming out. HELP?