my 3 year old kid is getting like this near his mouth its been thr since a week how to treat this ? what is reason for getting this

A. This is some internal infection that’s coming out like this it’s better to consult your doctor this is very difficult to say what can be the reason behind it but this is commonly seen happening on the body of the child usually sometimes on the elbow sometimes on the hands feet on the legs somewhere you have to check with your doctor for better clarity over the situation and treatment to follow