Meloxicam is a fine pain reliever in birds. Enroflocin is a broad spectrum antibiotic used in many birds. Myself personally enroflocin isn't my favorite antibiotic in birds, it can cause some stomach upset , but so can other antibiotics, it can cause a secondary yeast overgrowth, but again so can other antibiotics. Something to watch out for. But yes, it is an appropriate antibiotic used in birds.
Can you share how old is your bird? What does the bird eat ? Diet can play a role in preen gland health, if the diet is lacking proper nutrition. Especially if low in vitamin A , vitamin A is best from diet foods like sweet potato, peppers, leafy greens, and other veggies or it's in pellets.
Sometimes preen glands get impacted and infected. Treating with med's d vet prescribed and healthy diet can help resolve. Sometimes this can be because of cancer in the preen gland , we had a member with a different species that was the case , and I have heard of it a few other times ..it is more rare , and not saying it just to freak you out , but just so that you are aware. Hopefully you sweetie is the more normal case and fully recovers!