Rashes
Rashes are nearly too broad of a subject to discuss here.
The most common rashes are allergic and appear as hives which are
raised, red and quite itchy. They frequently are associated
with exposure to animals, medications, foods, grasses, soaps and a
variety of other causes. Treatment involves benadryl (or
other antihistamines), prednisone (a steroid), and zantac (or
another stomach medication which acts like a different type of
antihistamine). In rare instances, you can develop difficulty
breathing, swelling of the tongue or throat or sores on mucus
membranes which all require rapid evaluation by a physician.

Hives
Additionally, infants can develop rashes that are due to
viruses such as a viral exanthem (which accompanies a cold),
hand-foot-and-mouth disease (a virus that causes ulcers inside the
mouth and on the feet and hands), ringworm (fungal infections),
scabies (a mite that burrows under the skin), pityriasis (a benign
rash that appears on the trunk and is usually without symptoms),
and infections such as impetigo.

Viral Exanthem

Hand-Foot-and Mouth Disease
More infromation at this link:

Ringworm
More infromation at this link: Ringworm

Scabies
More infromation at this link: Scabies

Pityriasis Rosea

Impetigo
More infromation at this link:Impetigo

Community-Acquired MRSA
More infromation at this link:
MRSA
More recently, methicillin-resistant staph infections have
been increasing in frequency and cause a rapidly progressive, warm
rash that requires antibiotics.