Pregnancy confusion

Hi all i know this is very weird but i have been following my period cycle on this app and i moved a hole week back after i didnt start the first week it was due. I have been experiencing a sharp stitch on my left abdomen and believe it or not but im very stupid with these things (pregnancy) lol:.. Could i be experiencing implantation. Im suppsed to start tomo by the looks of this app.  I have also been very moist ? which is very unusual to me. Please could someone help me with some valod and helpfull advise.