Hi The inner thigh rash is most likely to be a contact dermatitis...that's the classic site for it. This happens when a dog walks over or lies on something that he is allergic to. Most commonly this will be a plant species of some sort so have a think about where he has been lying lately (in the garden) or where you have been walking him.
On the top of the back the most probable cause is fleas. That is the typical area for a flea allergy dermatitis. Have a good look at the skin in that area….you will see the fleas or black grains of flea droppings. Make sure you clean up his environment and use a good anti-flea product like Frontline or Advantage.
To settle the rash down you can dose him with Benadryl Allergy (diphenhydramine) but ensure it is not the combination product (Benadryl Allergy and Sinus). The dose rate is 1-2 mg/lb but do not exceed 40 mg total dose. Any anti-inflammatory or soothing cream will be suitable for the inner thighs. Aloe Vera cream or Vitamin E cream is good. Creams are not so much use along the top of the back where the skin is thicker.
Kindest regards, Peter
Allergies to inhaled or ingested compounds can manifest anywhere but when we see a rash on the underside we usually consider a contact dermatitis first. So this occurs when the rash appears just where the patient actually contacts the cause. An inhaled or ingested allergen can occur anywhere on the body but most commonly it will affect all of the body simultaneously.
I’m unable to say if the lipoceutical glutathione is a likely cause. However if the rash suddenly appeared just after you started it then it would be very suspicious! Always think of something that has changed when there is an allergic reaction. I suggest you stop the lipoceutical glutathione and see if it responds.
You must restart the flea control (Advantage). Washing is not an effective way to control fleas. If you allow fleas back into your environment it can take a long time to get rid of them again.