Is it to soon to know?? 😖

Isabelle
So I had sex on cycle day 12-13 and it is now day 21 .. I been experiencing lower abdomen tightening sensation and slight headache and yesterday evening I was nauseous. But the wierdest is the lower abdominal tightness for 2 days? Is it too soon to know? Is it my imagination? Has anyone ever experienced this?
Help 😖