Feeling terrible, first time, I hope I'm not screwing things up

Hello,I'm new to all of this and these last few years I've felt awful. Im only 20 but I always feel like I'm having allergic reactions to everything, I feel weak and brain fogged like an old man, as well as experiencing hair loss and eczema. All of it seemed to start after moving to a new place when I was 15 and its only gotten worse since.

Well anyways I've decided to try iodine, as I'm most likely deficient so I ordered myself survival shield x2 nascent, and started with 1 drop a third of the 2000mcg serving size suggestion, and I've worked my way up to the three drops day by day.

At first I noticed that I felt warm and more clear headed, I was a bit more aggressive and confrontational, not anything crazy though. Overall I felt less allergic and weak, but then I started feeling a little meh so I tried the salt water thing albiet only twice the whole week and I think it made me feel better.

So far I have not been taking any other supplements alongside the Iodine other than vitamin d3 and some l glutamine here and there, I figure I'm getting selenium from food like eggs and sardines and I don't know if it would be too much selenium overall to take a supplement.

Well anyways I was still getting some brainfog usually later in the day, and I guess it was just a detox symptom, but I've also started noticing my thumb spasming and chest achiness, even palpitations so I decided to cut down on the Iodine and stopped it for these past two days.

After cutting down on the iodine, I feel terrible. I noticed that I'm more sensitive to cold again, my hands are dry and I've had an awful headache almost continously these past two days, I just dont feel right at all, very sickly.

I've still been having chest aches and muscle spasms, so I'm going to try and get some magnesium today but I'm unsure if I should continue with the Iodine or if I'll make things worse. It's only been barely a week of taking it, but another thing that's come to my mind is that I have a few Amalgam fillings and don't know if its bad to have while taking iodine.