What kind of fatty acid supplement is it? If it's something like fish oil, check to make sure it's not rancid. I would buy human-grade stuff from a good source that uses third-party testing for purity and freshness (like Nordic Naturals).
I wouldn't rule out the Benadryl, either. Meds can always have tons of side effects.
I wouldn't rule out the Benadryl, either. Meds can always have tons of side effects.