Rooster losing balance and sleepy.

[WeNeedDrPhil]

I'm woefully ignorant of what the regulations in Bulgaria are. A quick search indicates that you may be able to purchase them at a pharmacy there. Fenbendazole is a wormer that is used in humans also. Either that or Albendazole can be used to worm him if you can get some.
This article has a chart that shows medications that can be used to treat coccidiosis, scroll down for treatment chart, click on green box with arrows to enlarge.
https://www.merckvetmanual.com/poultry/coccidiosis/overview-of-coccidiosis-in-poultry
Amprolium is most common in the US, you will have to see what you can find there. If you are able to get anything, someone here will likely be able to help you with dosing if needed.
Also possible that the lump is a cyst, without biopsy hard to say. I would continue with the soft feed for a while and see how he does and whether you see improvement or whether the lump continues to get larger or not. Monitor his crop to make sure it's working well and emptying and he doesn't develop sour crop, which can sometimes happen if things are moving slow.

I think I might be able to get some tetracyline and albendazole at a pharmacy, but I think I need a prescription to get it, but I'm not sure. Any idea how to convince them to give it to me?

 

[Wyorp Rock]

I think I might be able to get some tetracyline and albendazole at a pharmacy, but I think I need a prescription to get it, but I'm not sure. Any idea how to convince them to give it to me?

Not sure how you can convince the pharmacy to give you meds.
You might be able to talk them into the Albendazole since it's a dewormer, but the antibiotic (Tetracycline) probably not.

I do wonder since he has that fatty bulge over his crop, have you felt him in other places - does he feel like he has a lot of fat under his vent between the legs? He may have a lot of fat surrounding his internal organs like one might see with Fatty Liver Disease.