Yep...those additional babies will do it to ya'!!! I was okay with #1--had the hernia but it went back to relatively 'flush' with my abdomen after baby was out (I've never had an innie, always more flush anyway). Not pretty the entire time I was pregnant (from about 3 months on), but hey, it was all good afterwards. And then yes, #2 comes into my belly and I looked liked like a turkey at Thanksgiving with one of those "I'm all done cooking" buttons. Ugly and didn't feel so good. The belly band will not prevent it as stated by someone else, but it can help ease a bit of the pain. Any counter pressure helps and Dr. recommended an ACE bandage which was itchy as all get out. The Dr. did put my mind at ease saying that if it were to rip or start to strangulate (where your insides really spill out past the opening in the muscle and then don't get enough blood flow and start to die basically) I'd have intense pain and to run for the ER. My muscles never went back together (its' been almost a year and a half since #2). My belly button is still huge and ugly and sticks out a bit past my abdomen (I'm a kind of smaller, so maybe if I had more padding it wouldn't be so pronounced?). But the great thing is that my husband doesn't care, so even though I'm done having babies, I may never get it fixed (or be caught dead in a two-piece!!!).
So of course I'd run it by the Dr. but mine really made it sound like I'd be doubled over rolling on the floor if it were an emergency, and again, nothing you can do to prevent it anyway. Kind of like how you know when you're really in labor : - ) Good luck and enjoy your babies.
P.S. My back is killin' me and I see you are a massage therapist. What general area?