Why does my dog have a persistent skin rash with bumps and no relief?

Poor guy. I would highly recommend asking your vet to perform a skin scrape on Tombo. These lesions are suspicious for possible demodexx mites. The trumectin is a Demodexx treatment; however, you didn't mention that your vet actually tested for this. If this is a mite problem, then a topical medicated shampoo can be used in conjunction with the injections to gain better control of the overpopulation of mites on the skin. Also there are several other products that treat for mites that may be more effective for him, such as the off-label use of Nexgard, Bravecto or Simparica (have to be 6 months or older, so this may be an option depending on his exact birthdate).

Also a skin culture should be done to determine which antibiotic will get rid of this infection for a certainty. Most skin infections will respond to broad spectrum antiobitcs, but there can be resistant infections that don't respond, which may be the case with your pet Tombo. This infection doesn't look particularly fungal in nature; however, if your vet already did a skin impression to confirm there is yeast present on the skin, then definitely continue with the Fluconazole treatment as prescribed.

These viable tests (skin culture, skin scrape, impression) should give us a good idea on how we should be treating him from here moving forward.

As a general rule of thumb, you can give you pet pet formulated fish oils for just about any skin condition in which the skin is red. Fish oils act as a natural anti-inflammatory and can also held with overall skin health. You can find these at your local pet store or through your vet office.

I would also inquire with your vet about prescribing some antihistamines to help with any itching that Tombo has right now. That will help him allow his skin to heal and respond to all the treatments he is receiving.

I hope this helps you find some resolve for Tombo's itchy/irritate and balding skin. Best wishes and take care!