Please help sharp pain

Hey girls 
​So last night about half an hour after me and my husband had sex I had this sharp pain in my pelvis area just off to the left. I'm not sure if it was maybe implantation as according to glow my fertile week was last week and af is due 22/3/14 or weather maybe I'm ovulating this week and it was just ovulation pains. Only reason I say this is because That I checked my cm today and it's a bit like fertile cm. if any one can relate or may know what it could be please let me know