Cramping 5 days after sex

Ms. E
Had sex on June 17 and 18. Now I'm having cramping that's annoying enough for me to take some Motrin. I was fertile during that time. Is it weird to feel cramping that early? Is it possible I could have conceived already? And why hasn't Glow predicted my next period? Someone please clue me in. I would hate to get excited over nothing.