Hi Cindy! You probably got an answer to this already, but size discrepancies are often the case when it comes to birthmarks on extremities. It's important to see a doctor about those things to determine if there are underlying issues.
And yeah, I can TOTALLY relate to both you and the original poster on this thread... I have a PWS that goes from the toes on my right leg, the sole of my right foot, and all the way up the back of my right leg. Mine changes color with temperature, too - and I used to really freak people out when swimming in the cold ocean and my birthmark would turn BLUE!
I have gotten "have you been in a fire?" a lot from folks. Sometimes I say, "why, yes, I have been in a fire. I was trapped for an hour with a burning beam on my leg. Thank you for reminding me of that horrible trauma." Yes, it's not nice of me - but some days, I'm just NOT in the mood to be tolerant and to educate, especially when people ask insensitive questions like that.
It's really good to find folks to relate to...