Not sure how you stumbled on a thyroid board on this question - but your question about headaches could be associated with your levels.
If you are concerned about your thyroid being effected from the blast. It would be good to ask for thyroid tests to find out.
My doctor said he was going to refer me to an endocrinologist after he got my new labs back. So I looked up endocrinology, and I got the thyroid forums.
I see. Let's us know whats happening.
Given the symptoms and history of TBI, I would strongly consider an MRI to look for damage to the pituitary gland (point at your temple and between your eyes and the pituitary roughly is where the lines intersect). If the pituitary is damaged, which can happen with blunt trauma to the head, levels of the hormones that trigger your endocrine glands (e.g., testicles) to make hormones (e.g., testosterone) can be significantly lowered. This leads to lower levels of endocrine hormones. Usually, it wouldn't just be one hormone, like testosterone, but others, including thyroid hormones, that are affected in that case. This could be the explanation for your symptoms and labs.
I am sorry superbrain - I have to disagree on the location.
Located at the base of the brain, the pituitary is composed of two lobes: the anterior pituitary (adenohypophysis) and the posterior pituitary (neurohypophysis). The pituitary is functionally linked to the hypothalamus by the pituitary stalk, whereby hypothalamic releasing factors are released and, in turn, stimulate the release of pituitary hormones. Although the pituitary gland is known as the master endocrine gland, both of its lobes are under the control of the hypothalamus.
Anterior pituitary (Adenohypophysis)
The anterior pituitary synthesizes and secretes important endocrine hormones, such as ACTH, TSH, PRL, GH, endorphins, FSH, and LH. These hormones are released from the anterior pituitary under the influence of the hypothalamus
I am sure that you are further along in your process of diagnosis, and education, so my reply may be redundant. Since answering your question on this forum has turned into an anatomical discussion, I'd like to directly respond to the questions you asked.
This link is to a questionaire, and helped me connect the symptoms to the condition of Low T. http://www.hotzehwc.com/testosteronetestman/. The symptoms you described can be related to the low-t, especially the depression, lack of energy, and sleeping issues. However, there are other situations you described that could be involved with the same symptoms. Also there are symptoms that you may not have.
Low - T is a catch phrase, mostly for marketing Testosterone Replacement Drug Therapy to the 25% of men that have below "normal" levels. However about 6% of men are so far below the level that gives Medically Professional Doctors real concern. Having your # at 25 is remarkably Low. Being 21, just makes this more unfair.
The usual cause is either a Thyroid issue, (and that is why some of us were directed to this forum from the web search), or some kind of direct damage to the testicles. In my case, the why is still unknown, but the therapy has been a positive life changer.
Good luck with your process. I know how difficult it is to cope with the effects of Extremely low Testosterone, and the problem of not feeling like a "Man". Just one piece of advice, do not blame yourself if you cannot "just work through it". There is a reason some of these symptoms can continue to persist, even though you are doing everything the doctors tell you!