Is this port wine stain?

[erbo]

My son is 2 months old. He is a preemie. He was born at 34 weeks and 2 days.
He didn't have this birth mark at birth. We found it when he was 4 or 5 days old.
I don't know if this birth mark is uncommon or not, but some doctors we saw cannot tell what it is.
It didn't get changed in 2 months and it will get darker when he is upset.
Is it a port wine stain? Please help us. Thank you very much.

Ps, Could you tell me how to upload a picture?

[missy]

To upload photo, go to "manage attachments." If you have trouble, email it to contact@birthmark.org and I'll take care of it.

Missy