Have i burst my stitches?

I had an operation a week ago for a Umbilical Hernia repair. Ive steadily been doing more activity such as walking over the week. The pain has been going and the swelling going down. However today i noticed that it isnt as hard around the belly on but the swelling inside the belly on is soft and spongy and a little bit red in the middle. It looks a little like it did before the operation, however before the operation when i coughed the hernia in my belly on protruded a little more, it doesnt do that now. How would i know if i have burst the stitches?