Movements....help

Mandi
I am a first time mom, plus size with the placenta in the back. So basically you can't tell I'm pregnant and I don't think I've felt him move. I'm 22 weeks this sat. My question is I keep hearing it feels like flutters or gas when the baby moves, but I feel quick pains then it stops. Like some one hit me from inside. It doesn't feel like gas and if it was ligament pain I would think it would last longer....anyone feel this or have any suggestions?