Hair Loss in Child?

My new doctor recently told us that my 3 year old step-son has alopecia. She didn’t get into specifics with it but said that his condition seemed to be improving on it’s own. He has a bald spot on his right side and it was really bad in January when he first moved in from living with his mother. Is it possible malnutrition caused his hair to bald? He was also extremely underwieght according to another doctor?

There are many causes of hair loss including fungal and bacterial infections. In children, fungal infections are not uncommon. Malnutrition would be unusual, particularly without dieting. Included are other conditions of genetic origin such as Alopecia Areata. If it is going away on its own and your doctor already has seen it, is involved, and is comfortable with your step-son’s situation, then just wait it out.