Why do I keep backsliding?

So my thyroid issues have been going on since last August. My primary started me on levo, intial dose was 25mcgs. And I about I started feeling better. Then around December, I started feeling fatigue again and having muscles aches. Symptoms that I started associating with my thyroid, even a weird eye twitch on my left eye. Primary rechecked my levels and then uped my dose to 75mcgs.

I was on that dose for a couple weeks when my Lyme doc offered to switch me to nature-throid. I wanted to try it since it is suppose to be natural and have T4 and T3. I didn't feel well on it at all, looking back, I think the dose was too low. But I panicked and went back on the levo. Started to feel better on that for awhile. But then I started to feel terrible again. Right now I seem to be sick on this weird in between area where, my tests were "normal " but I feel like crap. Awful fatigue, sometimes debilitating. Muscle and joint aches, I get a sight tingling in my hands and feet from time to time, insomnia, I can't sleep more than 4 hours straight.

My last visit to my Lyme doc she suggested I take extra zinc and selenium because she thinks my issue is converting my T4 to T3. Offcially, I've been on my on the extra zinc for 3 days. I need to find some Brazil nuts for the selenium.

Okay, so I know that was a long, very long, explanation. But did out for anyone else have this issue where you feel fine for a little while and then start to feel terrible again? I know I need to have my cortisol and adrenals checked, but I'm sure they are shot to hell. I don't eat gluten, I take vitamins, I take probiotics. I feel like I'm doing everything right but nothing feels like it's helping. Oh... And I was tested for hashimoto's back in 2014 and that was negative. I thought they would test me again but since my last test results were on the normal range, it was hard to argue for it.

Did anyone else have conversion issues too?