I take synthroid, am supposed to be taking 400mg of plaq but only take 200mg as well. I have only increased for short periods of time, but the symptoms you describe remind me of the symptoms I had when my thyroid medicine was slightly too high, or when I had problems with electrolytes and water balance. I had more problems when I was getting occasional prednisone tapers and injections.
I am having similar problems on Isoniazid for latent TB, which blocks the synthroid, but also stimulates the adrenals. I have secondary adrenal insufficiency because my adrenals still work but my pituitary isn't supplying them with ACTh to trigger them to become active. Prednisone can cause this but in my case, it is part of my autoimmune polyglandular dysfunction.
Because the isoniazid is killing the latent TB infection I have and taking the burden off my immune system, my pituitary is working better and my adrenals are freaking out, making me frighteningly hyper sometimes. Of course all this alters the thyroid too. My thyroid is getting worse.
Plaquenil being both an immunosuppressant and a disease fighting agent might be helping you alot more, since you get so much energy from it. I would get with the endo as many have suggested. I always try to get a cortisol test and ACTH stim along with the thyroid tests to see if something else is going on and figure out which med needs best be adjusted. I do think the plaquenil helps my thyroid some being an immunosuppressant but this is my gut feeling. My AI disease is well controlled on 200mg most of the time. Hopefully your endo will check you for the other endocrine problems since they are interlinked.
My endo told me to not always drink water but sometimes gatorade as I drink distilled water and it has no electrolytes. When my electrolytes are bad, I have lots of heart and panic problems, but also the thyroid has to be checked. I have thirst problems, excessive, then no thirst.
I've gone rightly to the ER for the chest stuff and even if it is my thyroid med or plaq, there is stuff they can do and they tell me I was right to be checked out just in case. They always put me on IV fluids to thin stuff out, either electrolytes or no electrolytes depending on what the bloodwork shows.
I'm still not taking the 400mg as requested every day, but plan to try again after I complete isoniazid therapy. Sometimes it just makes me feel yucky to take so many pills, but my liver isn't good. Probably just a mental thing though.
I wish you the best and will pray for you that you get it figured out properly. Take care.