Thanks both!
Went to the vet yesterday, he shaved the affected area which is now the size of the palm of my hand and gave us to gel which he said should clear it up in a couple of days.
He‘s slept more or less non stop since then, won’t eat, stand up, or go outside to toilet so went back to vets this morning. Vet‘s unable to identify the cause, heart and temperature are ok and although the spot is hot and inflamed his glands aren’t swollen so I‘m now leaning towards a bite of some kind or mites (just hope its not a ***** tick carrying Borreliose!
) but he‘s taken blood samples and given him antibiotics and painkillers and hopefully we’ll know more tomorrow. Baby grows, T shirts etc have all failed to stop him chewing so he‘s been sentenced to the collar of shame, poor lad :'(
I‘ve taken him off his Yumove for the time being but I don’t now really think there’s any link and we‘ll start them again once we‘ve over this. ( its exactly a year to the week since he had his spinal surgery! )