Poop problems? REALLY sharp stabbing pains when I have to potty or pass gas!

Madison💁🏼‍♀️ • Retailer// Married 6 yrs// Mommy to fraternal twin girls// surprise baby on the way!
***This is gonna talk about poop, so read no further if you're easily grossed out***
Not sure if it's because everything is so squished in there or what (I'm 35 weeks with twins) but it HURTS! Anytime I have gas passing through my lower abdomen or a bowel movement or if the babies around too much it hurts! Like, doubled over and can't walk pain! 
I've suffered with constipation my whole life and it's the same sharp stabbing pain, but my bowel movements are normal-looking and I'm using the bathroom multiple times a day. I even take colace and it doesn't make a difference in the pain! My husband is always thinking I'm in labor, but it's not labor lol. 
Anyone else feeling this? It's very painful to go from standing to sitting (squishes everything down I guess).
VERY PAINFUL. If you've experienced it, you know what I mean and you never forget it.