Thank you for all your answers and thank you for your kind words about my country. In Poland we love parrots so much.
Igor (his name) will have 5th birthday on the first of June. Of course, I want to take him to the vet, but because of the current situation, I mean #stayhome, I want to wait until everything calms down, so I would like to know how serious the situation is.
I get the impression that Igor sometimes breathes quite loudly, as if he had a runny nose. So it may also be related to this case..
The last time I was with him at the vet in August last year and everything was fine (he got praise from the vet and they even liked each other quite well). He had all the preventive examinations (faeces, blood, nasal swab) at that time.
About his eating.. Every day for breakfast he gets a plate with something from this (depends on season): banana, apple, pomegranate, pear, strawberry, mandarine, kiwi, tomato, red/yellow pepper, cucumber, carrot, potato, corn, peas, broccoli, cauliflower, green beans, sprouts and naturally squeezed orange juice (e.g smth like this
https://imgur.com/bj95gBS). In addition, he also has a bowl with Versele-Laga African Parakeet Loro Parque Mix (he doesn't like another one) and he doesn't want to eat granules either. To be honest, his most common choice is his versele-laga and eating white millet from it..