I'm sorry Ezz is suffering from this issue, which can cause a lot of discomfort and is frustrating for owner and dog alike.
When it comes to flea treatment, not all are created equal. Though you have undoubtedly paid good money for both the shampoo and collar that you have purchased, they are unlikely to be effective (the exception to this would be the new prescription flea and tick preventative collar brought out called 'Seresto' which is superior to other collars on the market). I would remove his current flea collar.
Frontline is effective in some but we are seeing a lot of resistance issues in recent years, meaning many fleas are no longer affected by it. Regardless, it is only effective for one month so would no longer be active.
Non-prescription products bought online, from pet stores or from supermarkets are generally not strong enough to tackle the issue. They may kill some fleas but not all of them, meaning the fleas never go away.
We absolutely need to use a prescription treatment to deal with this issue. A spot-on such as Advocate or Prinovox is ideal. An alternative would be a tablet such as Nexgard Spectra. You will need to see your vet to be prescribed these products, but I can guarantee it is worth it. If you opt for a spot-on, remember he must stay dry for 1 day before and 2 days after to ensure it is effective.
Of course, any other cats, dogs or rabbits in contact with Ezz will also need to be treated, ideally on the same day.
Similarly, as 95% of the flea burden live off the dog and in their environment, we need to treat the home on the same day as the dog. This means hot washing any bedding and blankets over 60'c, hoovering all around (focusing on dark/warm areas such as under sofas and behind curtains) and ideally using a flea spray such as RIP or Indorex.
As fleas carry tapeworm, most dogs who have fleas will also have tapeworms. Ensure he is up to date with a good quality wormer such as Droncit or Panacur.
If his skin is irritated/scabby or infected, he may well need additional therapy such as antibiotics. Hopefully this is not the case.
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