Need help losing baby wieght?

It's been 5 months since I had my son and while I have lost a good amount of weight, I'm having problems losing the rest. I had peeclamsia during pregnancy so I gained 70 pounds and lost 30 of it in the first month after delivery, I have since lost about 15, but my progression has stalled and my stomache is still very "squishy", although there is muscle underneath. Also is there anything I can do to help get rid of stretch marks, I've been using cocoa er, but it isn't really helping.