I don't want to freak you out but itching without a rash can indicate a serious problem. Hopefully it is nothing but you should definitely follow through and get the bloodwork, etc that the doctor recommended. I pulled this off a website.
Itching may be caused by a skin disorder or by a disease that affects the whole body (systemic disease). Skin disorders that cause severe itching include infestations with parasites (such as scabies, mites, or lice), insect bites, hives, atopic dermatitis, and allergic dermatitis and contact dermatitis. These disorders usually also produce a rash. Systemic diseases that can cause itching include liver disease, kidney failure, lymphomas, leukemias and other blood disorders, and, occasionally, thyroid disease, diabetes, and cancer. However, itching from these diseases usually does not result in a rash.
Many drugs can cause itching, including barbiturates, morphine and aspirin as well as any drug to which a person has an allergy.
Itching is also common during the later months of pregnancy. Usually, pregnancy-related itching does not indicate any abnormality, but it can result from mild liver problems.
Often, contact with wool clothing or irritants, such as solvents or cosmetics, causes itching. Dry skin (xerosis), which is especially common among older people, can cause severe, widespread itching. Dry skin also can result from cold weather or prolonged exposure to water. Hot baths typically worsen itching.
The act of scratching can itself irritate the skin and lead to more itching, creating an itching-scratching-itching cycle. Vigorous scratching may cause redness and deep scrapes in the skin. In some people, even gentle scratching causes raised, red streaks that can itch intensely. Prolonged scratching and rubbing can thicken and scar the skin.
Here is the link so you can read the rest of what it says.
Hopefully everything works out fine. Good Luck!!