Could I be pregnant ?!?!

I don't know if I'm experiencing implantation bleeding or if I'm spotting. I had a miscarriage a month ago and have not had a period since which I know is normal. I had sex 12 days ago and I'm not sure when I ovulated. this past week I have been extremely tired, no appetite, three days ago I woke up naseous but did not throw up and the past two days I have been waking up in cold sweats. I have had cramps and mild back aches and have started spotting only when I wipe after the bathroom. This has been happening the last two days and it started out brown and it's slightly a little reddish today. am I about to start my period or?! Please help!!