A pws is considered a Vascular Malformation. The two most "common" types are Port wine Stains and Hemaginoma's. There are other types also.
PWS does not go away, unfortunately. It can be lightened with laser . With the current laser technology,pws is usually not eradicated 100 percent.
A Hemaginoma is different than a pws in a few ways. A pws normally stays flat. A Hemaginoma can change in appearance and "grow". Not all do. A pws is forever, where most-but not all- hemanginoma's involute with time. They can treat a Hemaginoma with laser if the doctor feels it will be beneficial.
My advice to you would be to see a Pediatric Dermatoligist as soon as you can, so you will know what your child has. Knowledge is power. Once you know what it is, if it is a Vascular issue, you can see where you need to go from there.
I wish I could help you more.
It is hard without seeing what you are talking about.
After you see the doctor, if is is a vascular issue, there are a lot of people here who can help point you in the right direction, share their experiences and provide support if needed. I am more familiar with PWS, but Corinne is a wealth of information about Hemanginoma's.
Please keep us posted.