Hello, thanks for your question today! I am Dr. Drew, and I am a licensed veterinarian. I'll be happy to help you in any way I can.
Alopecia is simply a term meaning "loss of hair",
and it does not identify the underlying cause.
If there's no itching, redness, or scabs/crusts, then allergy is unlikely to be an explanation.
Skin scrapings should be done to identify Demodectic Mange, which is caused by a type of mite living in the hair follicles. It does not cause itching for the most part.
If that's ruled out, then typically the next step is bloodwork to check for any evidence of hormonal imbalances such as a low thyroid or an over-active adrenal gland,
though both are uncommon at such a young age.
If no cause of the problem is found, then this may be a genetic issue,
and I'd suggest Melatonin, 2-3 mg daily, to see if there is any hair regrowth over several months.
Melatonin is very safe,
does not cause any changes in "character"
and can be used long term without any known adverse effects.
A change in diet would not be expected to provide any benefit unless signs of an allergy are present, as mentioned above.
Since I have not received a reply from you, I will change this chat into Q/A format for your convenience.