My father had a malignant melanoma removed from his nose, together with approximately half a centimeter around it. A couple of days after the operation, the wound looked fine, that is to say it was clean, clear and showing no signs of weeping. However today - Sunday - (the operation was performed on 16th February) - I have just dressed the wound and noticed it is weeping slightly, plus there is a flat, yellow area in its centre, which I am guessing, is pus. Why is this? especially when the days before it was find! Can anyone help please?