Hi,
Are they around the areas you have been injecting him?
Can you get us clear pictures?
The RI may not respond to a particular antibiotic on occasion which is why people recommend getting a culture done even though it is an extra expense - it lets them see which antibiotic works best against the infection.
Have you finished the whole course? The vet might want to repeat it or try something different but if you have finished and he still has the RI then the vet needs to see him again.
dr del