Quick question

My calendar said 7.8 chance of pregnancy last week Friday . And I had intercourse and he "cam" inside me , now five days later when I wiped my self earlier today there was a pink dot on the tissue . I wiped again I didn't see anything . I use the bathroom threw out the day and didn't see anything else .Couple hours later at night again I use the bath room and I see the pink dot again I wipe n didn't see anything. But right now I have the worst headache ever . N sensitive to noise .. Anyone experience this ?