Congestion and sneezing in cockerel

Hi so I lost a pullet 2 days ago to what we thought was a sinus infection, vet did too. We treated her with antibiotics etc she never recovered. She only had swelling under eye, no respiratory symptoms at all! Now my other lavender Orpington is showing signs of upper respiratory, gurgling and sneezing. Ironically the other 6 chicks are very healthy it's only the orps who get sick I have 2 Sussex from the same farm that are healthy. I'm wondering if it could be mold or fungi? We've recently had a lot of rain and there pen seemed damp and I noticed some white mold under a water dish. I've thoroughly cleaned and put in a lot of bedding, sand with shavings on top and hay where they sleep, it seems very dry now. I've had them all on duramycin since the pullet died. She was on clavamox which didn't seem to help her at all. Should I try Oxine? I've been reading about it on here for mold, fungi, viruses etc and Tylan for him as well as duramycin? Any advice on giving Tylan orally? Thank you! I'd really like to save this guy after losing her

I am a fan of Tylan 50, but have only given it through three days of injections. Tractor supply sells needles/syringes.

If you go that route, use the smallest needle they sell (higher the number means smaller the needle). A full sized bird could have 1/2cc - inject into the breast muscle, alternating breasts for three days. Much easier if you do in the evening when they're calmer -and have someone hold the bird firmly. Feel for the keel bone, and then the breast muscle on either side - inject there. If you're able to get 1/2 - 3/4 inch needle, you can just go straight in.

Thank you for the info! I was able to get some soluble Tylan from my pups vet Friday. We continued with the duramycin and added the Tylan as well as using the vetrx chicken remedy, we rubbed the oil on his nose/beak and head. He has rebounded great no sneezing or crackling in chest anymore and back to his active self! I'm so relieved, not sure what did it but he's better. Has anyone heard of lavender orpingtons being more suceptible to illness? Or was it just coincidence?

Glad to hear he's doing better. I haven't heard of Lavender Orpingtons being any less hardy than other birds. Respiratory illnesses can be easily passed from chicken to chicken regardless of breed so chances are he just picked it up and started showing signs of the disease.