A psychiatrist is a doctor who is certified in treating mental illness. Psychiatrists are the only mental health professionals who may prescribe psychiatric medication as part of the treatment process. Psychiatry is a medical discipline, and so psychiatrists are medical doctors per se. Thus they may conduct physical examinations, order laboratory tests and brain scanning.
One of the alleged reasons for the skin picking disorder is chemical imbalance in the brain, sometimes related to the chemical serotonin. A psychiatrist may prescribe medication targeted at balancing this and other kinds of abnormalities related to brain functioning and the chemical processes in the human body.