Your baby is having atopic eczema
Due to dry skin, baby scratches all the time.
Due to trauma after scratching , baby got bruise on shoulders.
Bruise is not the serious problem.
The main problem is atopy.
Keep baby's skin moist with moisturiser.
HCL syrup to relieve itching.
Take all precautions to improve atopic dermatitis
For this, you consult dermatologist
I hope you got my answer.
Dr. Ilyas patel MD