Is it too soon to notice an ectopic pregnancy?

Patient: I have a history of endometrosis and PCOS. Due to these conditions I have seek the help of a fertility doctor. He put me on Clomid and progesterone. I followed his “Clomid schedule”. If the medicine worked the implantation would have happened on the 20th of February. I am having extreme lower abdominal pain with shooting pain to my side. I have on and off nausea with no vomiting. I am worried about an ectopic pregnancy but it concerns me it is too early to have these signs. It is possible to have the S/S of an ectopic pregnancy this early?

Symptoms: Lower abdominal pain