Hey Cindy,
You've heard the expression 'no pain, no gain'? Well it's not true. Never do an exercise that causes pain in any part of your body. Absolutely, definitely cease doing those crunches.
Try this - lay flat on the floor with your hands under your hips and do some leg raises, both legs together, just a few inches off the ground and hold for 5 seconds each. Keep your head flat on the floor, looking straight up. Don't bend your neck to look at your feet. The abs will burn, baby burn, I promise. When you get stronger, take your arms out from under your butt and put them straight out, like a cross.
The ab roller might help, but watch out for getting momentum from rocking forward. It will nullify most of the work your abs are supposed to be doing.
Good luck.