Implantation bleeding or no ?

Hey ladies, so I’m kinda confused right on what’s happening. May 22nd I got my period it last usually 4 days. I had sex (unprotected) the 27th at night around 9pm , 28th, 29th morning and on the 31st I got a plan B. Today is June 4th and I have dark brown stuff in my panties and my stomach is cramping. Do you think is implantation bleeding or no ?