Is there a gap running down the middle of your stomach equal to or less than two fingers' width? If so, then you have a mild separation that will probably resolve with correct conditioning. Current wisdom states that a linea alba separation equal to or less than two finger widths is not a significant separation. My belief is that if you have back pain and are unable to generate enough abdominal tension to stabilize it, even half a finger's width is too much.
A pronounced separation wider than two and a half fingers requires more attention. If you see a small bulge protruding, this may be a herniation; you should contact your physician. In this
circumstance, exercise caution when lifting, sitting up, and performing rotating activities.