Clicking with a dirty vent?

[Howldaloom]

Ok i have a zebra finch male that has been clicking. I mostly notice it at night.

I treated him with antibiotics (Baytril) and it did nothing, then treated with scatt, no effect, then treated with acox for going light, then probiotics for 3 days, he is currently on ronex 12% extra strength but that also seems to be having no effect.

I noticed a couple days ago he has a dirty vent. It is white and crusty on his bum feathers. I provided a bath but no improvement.

And he is still clicking! He has NO other symptoms other then the clicking and a little dirty vent. (WHITE, not brown, red, yellow).

I am due to treat with scatt again in about 9 days and then im thinking of putting him on doxycycline for 7 days and then probiotics as im scratching my head here thinking what else can i do???

HELP!