upping selenium dosage

i'v been taking Iodine for about 2 months at 100 mg. lately i'v been feeling pretty dull, bad insomnia even though i'm extremely tired i just can't fall asleep.

my mind is normally very sharp and quick and now it just feels retarded. i can't concentrate, read much or remember what i'v read so well (normally i read a lot and have an extremely sharp memory especially for events even insignificant from a very early age).

i'm fatigued all day and don't have much energy to spare and every task seems like a big deal even small things like picking clothes up off the floor, washing dishes and going to the supermarket.

my personality also seems to have faded. normally i joke around a lot and discuss the topics i'm interested in a very lively manner. but now i'm passive and my thoughts r just confused and looping and i don't have much to say to anybody.

usually people find me interesting and engaging but now it just seems like my friends look at me like i'm weird and sickly. 

i just feel like giving up all the time like nothings worth the effort.

i thought maybe it was due to the amount of selenium i'm taking which has been 200 mcg for the past 2 years or more.

i went up to 400 mcg a day for the past 4 days and no improvement or noticeable difference.

today i took 800 mcg but started to get worried cause even in China i think thats the upper safety limit.

do these safety limits even take into consideration dietary consumption?

when people say a certain amount is safe to take like say 800 r they considering food sources?

i live in Israel where the soil is rich in selenium (so i have read). what if i'm getting a good amount from food sources already?

i don't know if to stick to 800 or go to less but i really want to feel better but i don't want to find out i took to much by having my hair fall out (whats left of it anyways) and all the other toxicity symptoms.

i have 2 kinds of selenium in the house one is Now brand L-Selenomehtionine and the other is called SelenoExcell by healthy origins which has High Selenium Yeast. i took 2 of each today cause i need to order more of the NOW brand.

lets say i keep taking 800 or even 600, how long should it take till i feel the difference?

i take all the co-supplements and more. any thoughts, advice or what ever?