Implantation or spotting

My period isn't supposed to come for 3-4 days , but when I wipe, there's a SLIGHT spot of blood which was hard to see but there. We had unprotected while I was on my period last month and he said he thought maybe a tiny bit got in me, but wasn't so sure about it. I'm not sure if it's implantation because we do have unprotected all the time or just a slow start to my period. I've also have random bouts of nausea that last 10 minutes every few hours for weeks now but I figured I was just sick.