It's good to hear the side effects are wearing off.

I don't think it's the antihistamines because I had just tapered and quit mirtazapine/remeron prior to starting quetiapine. Mirtazapine is a strong antihistamine and I didn't get any flu-like symptoms from it.

By the way, here's a nice description of the effect from increased dose quetiapine.
https://thelastpsychiatrist.com/2007...rticle_on.html