Yes, the thyroid and gastritis may be related to the eosinophilia and/or high IgE.
Eosinophilic Gastrointestinal Disorders can cause elevated eosinophil counts in the blood, and also high IgE. See www.apfed.org
for more info.
Thyroid disorders predispose to the development of allergies (IgE-driven).
Also, unfortunately, most parasite tests in the US are woefully inaccurate (i.e., very high false negative rate). The best test of parasitic involvement is to treat for parasites and see if symptoms and/or blood counts improve... Pinworms are one of the most common parasites (they're airborne, so very easy to catch).