Very early signs or just a bleh, weird week?

Je
My last period was 12/25, ovulating January 3-8. I had sex the 8th (last Sunday). I know it's very soon but I feel off. I feel emotional as ever this week. Crying at the drop of a hat, waking up dizzy with a headache the last three days & I am incredibly irritable. I felt a few cramps this week as well, very quick sudden ones. I don't usually feel this emotional this soon before my menstrual cycle, so it's a bit strange. Is it possible to feel signs this early? Or is this all in my head and is it just a crap week? Help!