I am really concerned that your son is suffering from skin lesions. Definitely children don't get skin lesions due to screaming. From the way you describe it looks like impetiginous lesions , which begins as red papules later becoming abscess
due to strep and staph bacterial infections. They can be treated easily with topical antibiotics or oral antibiotics
depending on severity.
However a direct observation by dermatologist
is necessary before starting treatment. Good hygiene in the form of cutting nails properly, washing hands regularly is very important.
Don't worry he will be alright. Take care.
Dr C Balaji