Hi I need help, a week ago my cat was spayed. After a while we discoverd a hard lump the size of a large marble were she had the incision. We talked to the vet and he said that it could be either a reaction to the dissolving stitches, or a hernia.. My question is how do you tell the difference? What should I do?? When is it safe for her to play with the second large male cat that we have?