I'm leaning towards your first hypothesis. As I have written already I was very anxious throughout my teenage years and it might have hindered my immune system's development. My hair got oily before I started working out, bulking just worsened it to the point that my scalp started to itch and flake and I was experiencing hair loss. I believe Seborrheic Dermatitis is a Candida symptom, and my take is that an intensive supply of carbs and Sugar during my bulking phase turned a mild Candida infection into a monster. As for the cold hands, I have had it for as long as I can remember.
Why did I develop all these symptoms ? Hundreds of people have adopted the bulking approach into their weightlfting program without having to deal with any of this, right ? It is because I had a weak immune system to begin with.
What do you mean by sleep pattern ? I have always slept 9-10 hours per night, sometimes a bit more, sometimes a bit less ; sometimes I have trouble falling asleep. Today I woke up in the middle night for example, but it happens once in a while. It really depends, I would say.
I did get my thyroid checked a few months ago when I came to the doctor to get vaccinated against tetanus ; I told her about my cold extremities issues, she told me that my thyroid was fine and that it was "normal", that some people just have it and that they have to deal with it. I was struggling with my Seborrheic Dermatitis at the time and was already starting to ask myself questions so I called bullshit.
My weight loss is due to my diet, I did intermittent fasting in order to lower my body fat that got pretty high. Now that I've stopped exercising and consuming Sugar altogether I am pretty slim, as I naturally was before weightlfting.
One VERY important thing I forgot to add : I have nonexistent libido. I experienced erectile dysfunction when I was weightlifting, but my interest towards women was kept intact still ; I have reached a point where it has completely vanished. I became addicted to p 0 r n & self-gratification back then to cope with my issues, I quit it cold turkey a few weeks ago because I suspected it to be the cause of my ED. As of now I am not so adamant about this since it could be a hormonal dysfunctionment as well. I just feel like I'm asexual.