When Someone is Not Sick, But Sick...

Patients with factitious disorders, formerly known as those with Munchausen syndrome, act as if they are ill but are not actually ill. They do however have a mental illness which causes them to mimic illness. They may lie about a condition, exaggerate symptoms, hurt themselves, or alter medical tests. Factitious disorder by proxy is when they falsify illness in another person under their care.  

Playing Sick?: Untangling the Web of Munchausen Syndrome, Munchausen by Proxy, Malingering, and Factitious Disorder by Dr. Marc Feldman at Amazon>>