Glad to hear that your son is going to be fine. There is definitely a connection between stress and how we are feeling with thyroid disease, and it can increase our symptoms. Stress also increases our cortisol levels (adrenal stress), which can lead to symptoms similar to those of thyroid disease.
I found a website that stated "Depressed thyroid and depressed adrenal symptoms are very similar. Cortisol, a primary adrenal hormone that is elevated under stress and depressed when the adrenal gland is exhausted, alters TSH and thereby T4 and T3."
Many of us take Vitamin B-complex on a daily basis to help out in stressful situations. It's not a cure-all, but does provide some support.