OK spoke to an excellent breeder (he's the one who sold me the Sultan, he's been breeding and showing birds his entire life and has an excellent reputation).
He never uses antibiotics and meds, always goes natural - well except for Tempra to treat sick chickens, stuff like that.
He said that little Phoenix needed a shock treatment to flush the infestation out of his system: 1/2 a clove of fresh raw garlic a day, for at least 5 days. I should then see a big improvement in his appetite, energy and general well-being. He promises that it has worked for his birds for over 4 decades.
If all fails, at that point I should be able to get some bird wormer (don't have access until Wednesday to an avian vet).
So I force-fed the garlic and ended up covered in dandruff flakes (the little guy objected at first), he's in really bad condition - no wonder he's stayed so small and unfeathered, he's getting no nutrition absorbed whatsoever!
He's been getting poly-vi-sol the since Friday and it seems to have helped a bit. Also scrambled egg with olive oil and cottage cheese, along with the chick crumbles.
hope this works
ps: also treated all the babies in the coop that had access to the same water as little Phoenix, since they are no doubt infected also. Smaller dose of garlic, but will do so for 5 days. The main flock starts treatment tomorrow, mashed garlic in their layer food (no other treats since they hate garlic and will have to be very hungry to eat the stuff!)
Will keep you posted!