Summarize the following:
If your itch becomes particularly painful or disruptive to your daily life, or if it persists for longer than two weeks of home treatment, you may want to visit a doctor for additional care. Call and make an appointment with a general practitioner, who can give you helpful diagnostic feedback and refer you to a specialist if needed. When meeting with your doctor, be prepared to share with them details regarding your general health as well as your specific itchy condition. Information that can be particularly helpful includes:  Skin conditions you’ve had in the past Locations and sizes of itchy skin patches A timeline of the development and changes of your itch Aggravating factors you may have identified Any associated symptoms you’ve noticed Relieving factors you may have discovered It is likely that your doctor will conduct a physical examination to help generate a diagnosis. Be prepared to show her or him the areas of your body most affected. Your doctor may also ask to touch your skin. In many cases, additional diagnostic work may become necessary. Here are some of the most common tests your doctor may ask for:  Blood test. Drawing blood with a small needle and analyzing its components in a laboratory can help doctors identify the internal conditions that could be contributing to the itchiness. Imaging tests. X-Rays, MRIs, or CT scans may help doctors find the internal conditions at the root of your itchiness. Chemistry screen. This type of blood test can help determine if liver or kidney disorders are contributing to the itch. Thyroid function test. A specific type of blood test, a thyroid function test examines whether a thyroid abnormality might be causing the itchiness. Skin biopsy. By removing and testing a section of affected skin, doctors can better determine what types of specific skin conditions are contributing to the itch.

Summary:
Know when you need medical help. Make an appointment with a general practitioner. Share relevant information. Receive an examination. Get additional testing.