Keep up what you are doing..... I would just keep massaging his crop and following the treatment suggested for impacted crop.... primarily. BE VERY careful... when you give the olive oil or any oral medication, food or water into him... that you do not put it into the airway... be careful to avoid the windpipe behind his tongue.. he would die rather quickly of "drowning" if you get anything into the airway. (Search -- "giving oral medication")
You can offer him some yogurt or buttermilk mixed with scrambled eggs / or mixed with some "complete" food, like "laying mash".. or wet laying pellets a little (then add some buttermilk or yogurt) and it will turn to a mash. Maybe you could put a little extra olive in that as well.
Just offer, don't force, the yogurt food mix...
I am figuring that he gets a complete food or some grit with his food regularly. And, the "respiratory" sounds, like "crackles", like he may have some congestion in his lungs or airway?? Does the info on impacted crop say anything about congestion or aspiration?
I don't know how old he is... or how old your hens are. Have you every wormed them all? Worms can cause a variety of symptoms, and if your chickens are free range especially and over five or six months old they could have worms. (Use the search here on BYC for "worming with Valbazen", or "worming" -- special attention to posts by dawg53 on worming, dosages, etc.)
But, I would continue to deal with this as impacted and / or sour crop first... then, afterwards.. if you haven't, consider worming everyone.
If you have more than one rooster, could they be fighting? Could your rooster have gotten injured or "beat up" by another rooster?
Good luck.
