He looks like a purebred chi... but a very badly bred one. He still looks very young in the second set of pictures... you can see his pink skin showing through. He doesn't look sickly, just poorly bred. A lot of chis have thin coats, so the pink skin can easily show through.
My Chloe is white (well, she is white with blue merle markings and blue eyes) and here is how she looked as a young puppy. She looks nothing like that puppy, and she is white:
And here is my Rylie (bottom of the puppy pile) and her litter as young pups... she was champion sired and well bred: