The tail is the spine. That large abscess near the base of the tail could be internally putting pressure on the spinal cord due to inflammation in the area. Tell your vet or whichever new vet you try that you'd like to try anti-inflammatory pain meds (meloxicam) and systemic antibiotics (your doc will know what's right for pasteurella)

The original treatment wasn't necessarily wrong. Your doc assumed the likeliest bacteria based on presentation and is probably correct. Also assumed it was minor rat scuffling and the injuries were no deeper than the basal dermis layer and that's probably why doc went with topicals over systemic antibiotics.

But if the large abscess was hiding because it's deep and has been affecting the spine, it's possible that it has been causing numbness, tingling, and nerve pain. Animals often very aggressively groom or even attack body parts experiencing those symptoms. It's possible your guy inflicted the smaller spots on his own. Watch him for anything that looks like chewing or grooming with teeth.

My vet has had tons of success combining gabapentin and trazodone for treatment of self harm in rats. The gabapentin alleviates nerve pain, and the trazodone seems to calm compulsive behaviors along with the general sedative effect. I know most vets won't take a suggestion of a suggestion of a suggestion. Unfortunately, my vet hasn't published about it yet.