There arent many medications specifically for avians. Amoxicillin is issued as "for dogs only!" and they put my cats on it all the time. Same thing with doxy, it has a warning on the label for human use only
Another mg dosage says for cats only but we use it for birds all the time. So as far as that goes, the warnings aren't always 100% accurate.
If you're truly unsure about the medication or the treatment plan, your best bet is to get a second opinion from another veterinarian. We can give opinions based on past treatment for our birds, but to get true, qualified
medical advice a medical professional is always best
I can say my birds have been on metronidozol before with no complications, but i don't know the supplier or dosage to properly say if it's good in your individual case or not. I've had no experience with clinsol specifically, but I have seen clindamyacin used to treat parrots as well. Again, without knowing the supplier and dosage it's hard to say and I'm not really qualified to say whether it's safe to give your bird. Sorry to not be of more help! The trick is each medication can be suspended in a different solution, different dosages, different inactive ingredients... that's why your best bet would be another avian vet, they're much more familiar with these things!