If you are dealing with MG (mycoplasma,) tetracycline and oxytetracycline are drugs that can treat it. In Canada, antibiotics usually have to come from a vet, unless you have your hands on some. Other antibiotics used are tylosin, doxycycline, Denagard, and others. Here is a good article about MG:
https://extension.umd.edu/sites/ext... Mycoplasma gallisepticum (MG) Infecti....pdf
https://extension.umd.edu/sites/ext... Mycoplasma gallisepticum (MG) Infecti....pdf