My stomach muscles look odd when i do a sit up, is this a hernia?

Maybe: If you are describing a general bulge in the midline above the umbilicus, it is a diastasis recti, and not a hernia. A bulge in the umbilicus or groin would indicate. Hernia. A surgeon can determine which condition you have.

Hernia: It may or may not be a hernia. Does the middle of your abdominal wall rise up like a hump when you sit up? If so, that may be a rectus diastasis which is not a hernia but often mistaken for one. See a hernia surgeon and they should be able to make a diagnosis.