You've read misinformation. The wormers currently sold are broad spectrum wormers and eliminate most worms, particularly roundworms.I have read the complete opposite- that each worm treatment only kills THAT SPECIFIC WORM species. It is all over every website I read. Can you please tell me where you are getting your information?
Also- I am in canada, and I do not have an avian vet who will be prescribing- just buying at local farm co-op. (like a tractor supply but not).
That is a maggot in your photos.