Sounds horrid and very frustrating. Bronchiolitis is viral (related to the common cold virus) - dd had it at 3 months, almost exactly 4yrs ago - but perhaps it is possible to get a bacterial infection as well. We did the symptomatic treatment - paracetamol, humidifier (or wet clothes on radiator), fluids in small sips (she was sicking back b'feeds so I gave very small amounts of ebm every hour or two) -and she took over a week to recover but then picked up a UTI and ear infection. It is very worrying and lots of babies every winter need hospital attention due to it, as it is very common at this time of year.
Hope he picks up tomorrow.