Hello Lorraine, I'm Dr. Deb and I'll do my best to help you today.
I'm sorry for this concern for Sire but it sounds like he may have a condition called Moist Dermatitis (aka a Hot Spot).
These lesions are usually created by a dog over-scratching (or over licking/chewing) an area of their body to the point where it becomes quite red and inflamed and can become infected in the worst cases.
We don't have a good understanding of the underlying cause of this behavior but allergies have been implicated for some dogs.
Another possibility is an abscess.
Regardless, I would suggest the following:
1. Trim the fur away from the area as much as possible. You can purchase very inexpensive mustache trimmers from a dollar store (at least you can here in the States).
2. I would clean the area with dilute betadine/iodine (to the color of weak tea) twice a day and let it dry. Your antiseptic wash should be fine, too. I would avoid hydrogen peroxide since it can retard healing and alcohol will burn (which you probably already know.)
3. Then I would apply over the counter topical antibiotic ointment such as you would use for a wound on yourself.
4. I'm a huge fan of a spray called Vetericyn (LINK) but it may not be available where you live (although it can be purchased on the internet).
5. Benadryl can be given to help reduce the tendency to scratch the area (if he's doing so). The dose would be 1 mg/lb twice a day with sedation a common side effect.
6. Aspirin can be given if the area is really inflamed and red.
I'd treat the area for 3-5 days and if there's no improvement, then I might have him seen.
He may need systemic antibiotics if this is an abscess.
I hope this helps. Deb