Are you using iodized salt? Iodine in your vitamins? Eating sea food? Note that there are no useful amounts of iodine in sea salt, lost in crystallization. You do not want to be treating an iodine deficiency with thyroid medications [you may still need those].
Check your waking body temperature before you get out of bed. Record this for a while.
Get and retain hard copies of your labs. Post results and ranges. NEVER accept "normal" from a doctor. You have to manage your own health care.
Read the stickies, you have a lot that you need to understand.
There are quite a few here with such problems at your age. And some who have such problems who have lost a lot of weight.
waist size= [how changed]
describe body hair and facial hair
when did you start and complete growth? sudden or steady?
changes to skin, hair, nails?
when do you think your T levels dropped?
any blows to the head prior to that? whiplash? concussions?
any reduction in peripheral vision?
testes ache, ever? -during a fever?
blows to the testes?
what drugs? - Rx and OTC -can change hormones
take anything to 'burn fat'? ephedra?
hair loss medications? ever?
You need to these labs at a minimum:
FT free testosterone
TT total testosterone
You should not self medicate as you need to know what is going on now by doing the lab work first.