Sayang, pain like that at 27 weeks, especially when it's stopping you from walking or sitting, really needs a doctor's check ASAP, okay? Don't wait for the next scheduled appointment, just go to your clinic or hospital today so they can make sure everything is okay with baby and your C-section scar area. I know a few of us mums had pelvic pain in the second pregnancy (our bodies remember!), but unbearable pain that bad needs proper checking, could be ligament stuff, could be scar tissue, could be something else, and only your doctor can tell. Jangan tahan, go get yourself checked out today. Sending you a hug, hope you feel better soon.