5 yr old healthy girl has one jelly bean size slightly raised, scaly sometimes itchy and tender skin lesion I guess on her left up chest near shoulder?

Get the diagnosis. There are many types and causes of skin rashes. Several types of inflammatory conditions of the skin, allergic reactions, and sometimes bacterial, viral or fungal infections can cause rashes on the skin. Insect bites can also be the cause of a rash on the skin. Have it evaluated by a professional and get the appropriate treatment.
Umm, hard to say. Skin rashes/lesions are most difficult to diagnose without actually examining them. How long has she had the lesion? Since the area is itching & now raising concern, perhaps it would be wise to have your pediatrician or dermatologist examine this in person. Then specific treatment and preventive measures could be discussed with more accuracy. Itch relief itself can be a blessing & worth the visit!