Possible Clues:

• Tinea
• Wretched fellow on call's got a fungal infection
• Call wife or mistress initially making a complaint
• Irritating infection — call wife or medic initially?
• Infection with raised edge? Wrong treatment injected
• Fungal infection of the skin characterised by round patches
• Problem with skin has grown, spread into lip
• Skin problem got from a disgusting boxer?
• Call and get back a bit of music on the line - it gets under your skin
• Phone line set up beginning to malfunction, which gets under one's skin