Hello, I'd like to help you with your question.
It sounds like your husband's illness might have triggered an emotional reaction, possibly from a past trauma. If he already has anxiety and has suddenly developed a depressive episode, then there is something from his past that is unresolved. Going to the ER for medications was a good idea. Medication can help him cope until he can take further steps to help him work through his feelings.
The first step your husband should take is to see a therapist. He needs to get to the root of what he causing him to experience these symptoms. Though depression and anxiety can have a biological component, more than likely your husband has an unresolved trauma from his past. It could be abuse or an incident that occurred to him that he never dealt with. Even if he does not recall anything that happened to him, he should still see a therapist. Sometimes people are so traumatized they block the memory. The therapist can help your husband explore his past and find out what is causing his symptoms. Here is a link to help him find a therapist to fit what he needs:
He can also use self help to address his symptoms. Here are some helpful links that he can use to learn more about anxiety and depression so he has better ways to cope:
On line links:
The Anxiety and Phobia Workbook by Edmund J. Bourne
When Panic Attacks: The New, Drug-Free Anxiety Therapy That Can Change Your Life by David D. Burns
The Cognitive Behavioral Workbook for Anxiety: A Step-by-Step Program by William J. Knaus EdD and Jon Carlson PsyD EdD
Coping with Anxiety: 10 Simple Ways to Relieve Anxiety, Fear & Worry by Edmund J. Bourne and Lorna Garano
Support is vital to helping your husband feel better. It sounds like you are there for him, which is great. He can also benefit from support groups and help from family and friends. Just by being able to talk out his feelings and knowing others care, he can cope better with what he is going through.
I hope this has helped you,