I don’t think you are in emergency territory, but since he’s sneezing a lot and you can hear him breathing, I suspect a respiratory infection.
Pine shavings are very dangerous to rabbits (the compounds in the pine build up in their systems), so those should be removed right away, and could certainly be affecting his breathing.
A safe and affordable option are pine pellets (sold as horse stall bedding, wood stove pellets, or feline pine cat litter). The way the pine is processed to form the pellets removes the harmful compounds so they are very safe.
In light of all his recent symptoms, I do recommend you take him to the vet. Like I said, it doesn’t sounds like he is in an emergency state, but he still sounds like something is going on.
Are his poops looking good now? Regular, frequent, round?
If he stops eating or pooping, then you need to get him to the vet ASAP.
The shedding plus itching could actually mean he has a skin infection or something similar going on. So yeah, call your vet
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.