Hi welcome to H.C.M.Forum .You are tired by going to the doctor means we wont find the solution. the child has got a boil & resuted to cellulitis
. if you leave it it may become still worse. more over the is very little and delicate so needs immediate treatment.I advice you to consult a pediatric surgeon or a general surgeon
.The child may need to be operated for draining the pus.wishing for good health of the child.