I just read the story and all the responses and I have to say, this has me scared out of my mind! I wish something like that would happen to me. But
anyway, I looked up Vassago on Wiki and this is the most interesting bit I got.
There are some ancient descriptions of the demon and its appearance. Below are a few quotes from various magicians who have called on this demon
spirit. Fact or fiction, they are interesting...
One early description of Vassago was that he appeared "as an aged man riding a crocodile and carrying on his right wrist a Goshawk. His eyes are
hollow and see into other dimensions, but he is blind in this dimension."
...
James Donahue - Vassago: An Impish Spirit
Vassago enjoys changing form and has been know to play games with magicians that call on him. Once seen as a dark and menacing entity, in recent
years he is now being thought of as being, playful, and mostly harmless.
-
Wiki
Please post pictures!! You should show us the pictures of the footprints as well. This is so interesting.
And next time, don't run away so fast. According to legend, Vassago can tell the past and future, find hidden things and has a "good" nature. So
you shouldn't be scared.
Oh wow, I can't believe I'm taking this seriously.
But it's interesting nonetheless.
I hope everything works out and you can find out what he wants. 
Don't be too afraid, if you keep running away, you can't ask
him questions!