New here n trying to understand

Hashimotto's disease is an autoimmune disease. You will be easy to catch colds and such (at least for me this is so).
See your doctor if you develop bronchitis from the cold.
If you have to take steroids it will mess with your thyroid levels for a couple of months, but level out after that.
Take your vitamins, get enough rest & sleep, take your medicine, exercise, and eat the right foods.
Another good tip is to go to your local bookstore and get the book "Thyroid for Dummies". It explains thyroid issues and diet in great detail in simple terms that a layman can understand. It's been my guide for years.