The endoscopy certainly won't show low stomach acid. It can show signs of irritation or inflammation which may be consistent with excess acid. It can show evidence of acid leaking (reflux). However, it doesn't measure stomach acid precisely - that's done with the pH manometry.
I have eczema which is triggered by food allergy and intolerance. Have you tried, given that you also have migraine, a low allergen diet? A detox can often cause aggravations - foods are eliminated which can actual heighten the allergic reaction when they are (unknowingly) reintroduced. Can you find anyone to help you do a proper elimination and challenge diet?
I have experimented with many many natural remedies for my stomach, largely to no avail. However, when I took a teaspoon of olive oil daily, hey presto, no eczema! It cleared up in about 5 days - so that's a cheap experiment that might be worth a go!
New stuff: GERD, Recurrent cystitis/Overactive bladder
Lifelong stuff: Food allergies/intolerance, eczema, asthma