@gladbead,
Quote:1……. "…. chaos, Dr. Thom continues to thrive."
Yes but you can omit it, as a matter of style. In general, use a comma where you need a slight pause
You might also say, "Dr. Thom continues to thrive [but] in an environment of constant chaos"
Quote:2. "…..to become allergic, to become sensitive…..." Is the comma correct?
Yes although the meaning isn't clear. I suppose however that's because it's out of context
Should it be a semi-colon?