Dog suffering from red, itchy, bumpy skin and ongoing ear infection

My dog is a Pit Bull/Staffordshire Terrier. Mostly white fur (very thin fur) with a few brown spots. His right eye has heterochromia iridum of blue and amber. When healthy his skin is light pink (if outside too long he will get sun burned). He is 18 months old and about 53 pounds. He has a very long and lean body type for being a Pit mix (doesn't have the usual bulkiness that Pit's have) and long legs (you can see hip bones and vertebrae, vet thinks this is fine, I think he is too thin).

When we first got him he was very healthy and happy.

Over the last 6 months or so he had many issues with his skin.
He has had multiple skin infections and ear infections of the left ear.
The Vet first prescribed an oral anti-biotic, oral anti-histamine for 30 days, Anti-biotic/Anti-fungal shampoo for 30 days and ear wash for 2 weeks for a yeast infection in the ear. After taking these his skin infection cleared up right away and his ear seemed better. Immediately upon finishing these prescriptions all of his ailments returned.

We took him back again and this time she gave us more of the shampoo and ear wash and some ear drops (did not give more antibiotics or antihistamine). I thought he was allergic to his food (we've tried 5 different varieties with no luck). The Vet thinks it's allergies from outside and maybe food also. She put him on a very expensive prescription dog food. He ate that for about 6 weeks and still had the same issues.

Here are some of his personality traits:
- Loving to our family, but weary of neighbors at first and then warms up and down right scared of strangers.
-Loves our other 2 dogs and is very rambunctious/playful with them, but absolutely hates other dogs. Likes our cat.
-Pees when scared and when he gets excited, when people lean over him and upon meeting new people.
-When he isn't feeling well from his skin issues he gets depressed/down and not his usual happy attitude.
-He will scratch at his left ear until it bleeds, will scratch at skin until it bleeds, will lick skin (especially his stomach area) until it gets red, scaly and gooey.
-Gets hives from time to time. Hives once popped up after feeding raw chicken.
-If we do not bathe him with the special shampoo every 2 days (as prescribed) his skin gets red and itchy.
-Is hungry all the time, will do anything for food.
-Is very smart and knows many tricks/commands.
-Is very protective of me (I am home with him all day, I am female).
-Likes walks, and getting in the pool with us.
-Hates having medicine put in his ear and will snap at you and do anything to get away (his ear is very sensitive). The ear will get a yellow wax like substance that will turn brown and then the whole skin of the ear will get a yellow scab-like scale to it and crumble off. Smells yeasty.
-When his skin is red and itchy he will lose fur.

I started him on coconut oil in his dog food last week and will start probiotics when I receive them.

I gave him homeopathic ear drops today after his bath. I have given these drops to our other dog when she had an ear infection and it cleared it up on the first dose. Also, told my Mom about these drops and they have cured her dogs chronic ear infection also. The drops have Chamomilla 10x, Mercurius Solubilis 15x, and Sulphur 12x. Please let me know if I should continue with these drops.

Please let me know if there's anything else I need to answer and thank you in advance for helping!

Cara