Is it implantation pain?

I did the deed last Saturday...so 7 days ago...but I was only about 10 days past my last period and I am normally on a 28 day cycle so would expect to have ovulated on wednesday or Thursday last week....today I had a sharp pain in my lower left abdomen...like a few pinches....it was enough of a pain for me to stop and notice it but not REALLY hurty....could that have been implantation? Or bec ause I did the deed 4 days before I normally ovulate is it impossible...or could the sperm have survived in there for 3 or 4 days? Eeeeeek..I feel a bit like I have a bun in the oven....! Any thoughts please?