Hello, and welcome to Just Answer. From the description you have given, I would probably recommend a vet visit. There are only a couple of things I've seen that causes the signs you have described. The most common thing in my area is biting flies. We are not seeing many of these at this time of year, but I can not speak for the fly situation in the U.K.
The other possibility would be a possible auto immune disease. These typically requires medication to suppress the immune system. This would not be an emergency, but I would not put it off too long.
If you cannot get Polly Bob into your vet for a couple of days, you can try a topical antibiotic like Neosporin until you can. This should help with the open wounds.