Get Pet Questions Answered by Pet Experts
It sounds like he might have a little clipper burn from being at the groomer's. For tonight, you can apply a small amount of cooling gel (after shave cream will help) after you wash the area well.
Keep in mind that this is a contact burn of sorts so you should treat it as such. Aloe and lanolin work well as does any other burn medication.
If you don't see any improvement by tomorrow, you will need to see your vet.
Let me know if you still have questions.
A hot spot is formed when there is a cut on the skin and bacteria gets in the cut. It's usually a wet area that the dog has been licking. This moisture promotes bacterial growth and the "hot spot" is the result.
You usually don't see a hot spot on the testicles but I would not rule it out.
If you suspect a hot spot, you can clean the area well with betadine or peroxide. Then dry it completely. You can then apply a small amount of neosporine or other antibiotic cream.
If this does not help, you will need to see the vet.
Hope this helps!