You're right, GERD is often the sign of underlying issues such as candida overgrowth and parasites. Those critters weaken terribly your digestive organs, especially the liver. Than other organs are affected: enzymes production by the pancreas, low stomach acid and so on... The fact that raw garlic gives you insomnia is probably due to the bad bugs dying, releasing even more toxins.
Diets alone won't work most of the time, but are effective if used with appropriate herbs and supplements. The key is to restore the digestion. Good stomach acid, good bile production, good elimination of toxins through mainly kidneys and colon...
For that, I suggest several things:
-Regarding diet, you better should consume high amount of raw vegetables and fruits in moderate amounts temporarily (due to the possible candida overgrowth), good oils such as coconut, olive and pumpkin seed oils, and restrict animal proteins to a minimum. Also, practice food combining: fruits always on an empty stomach for example. You can also add apple cider vinegar to your protein meals.
Juicing is also a great addition. Beet juice is the ultimate liver detoxifier and will keep the bile flowing. A healthy bile flow inhibits bad bacterias and parasites from growing. Raw cabbage juice has worked wonders for targeting GERD symptoms.
-Regarding herbs and supplements, there is a number of things you can use to accelerate the healing process. Milk thistle taken with meals will help the release of bile, as well as protecting liver cells from toxins. You mention Aloe Vera, which is mildly antifungal and helps with inflammation.
To kill the bad bugs you might have, there is a huge amount of supplements out there. But they can be very pricey. Raw garlic as you mentionned is cheap and proven very effective. To target possible parasites, use a strong Black-Walnut tincture (also antifungal). The spice turmeric is very effective against both fungus and parasites, as well as being a great liver detoxifier. Cayenne pepper will strengthen the circulation and help with secretion of gastric juices. There are in fact so many you can use.
-Also, forget expensive probiotics, especially if you already noticed they help very little. Most of them are not potent enough to make it to the gut, and the probiotic counts are usually far too low.
Instead, look into making your own homemade milk kefir. Kefir, a probiotic drink, is really a very effective and cheap remedy for most gut issues. And so easy to prepare. It is proven to be antifungal, antibacterial and antitumoral. The bacterias and yeasts present in kefir will directly kill candida and possible parasites, as well as colonizing the gut. Probiotic count of kefir is far more important than any expensive probiotic pills on the market.
Also, in the more "extreme" category, I suggest you look into Liver Flushing and enemas. Today, most livers are packed with stones that hinder the liver to do its job properly. Beet juice is very potent for thinning the bile, but won't release many stones that you likely have.
Enemas will help the elimination of toxins. Kefir retention enemas are one of the best addition to make, they will directly kill any bad bugs present in the colon and help recolonizing it with friendly bacteria.