you need to do a lot more study and investigating of these things. taking your temp under your arm means nothing. it could be a degree lower there anyway.
you need an accurate way of measuring your temp and you must take it upon awakening, before you even move a muscle, and throughout the day in order to find what your average is.
it has been a long time for me but this info is out there and readily available. sounds like your gut reaction is right and you have a thyroid problem. it can also be candida. it can also be your liver. it can also be your gut flora, or lack thereof, from Antibiotic
use. it can also be leaky gut, lack of vit b12, lack of nutrient absorption - and it is probably a combination of these things. i took my 96.5 degree temp up to near normal all by myself. but it took a while and the key is diet, exercise, fresh air, proper hydration and sunlight. i paid 200 dollars cash to a naturepath just to tell me that and then try to get me to buy all their supplements and books on Blood Type Diet
and crap like that. luckily, i had already given them all the money i had. save your money and work toward those goals, accepting no more losses and making gains every day, no matter how tiny. you can go as fast or as slow as you want, but you can do it. unless you WANT to be on medication the rest of your life. the first place to start so you dont bail a leaky ship - stop all meds and remove all amalgams. dont ask me how i knew.