How do I now get power of attorney for my husband?

Read your power of attorney. See what it says you are supposed to do in order to activate the POA. They are not all the same.
You should consider contacting an elder attorney to go over your and husbands new status to make sure you are acting in both your best interests.

You mean I can't declare him incompetent now He has signed the durable Power attorney years ago. I want to sell our condo and I will need power of attorney to do that.

Do you mean the Medical POA? There r two, financial and medical. Both should have been written up at the same time. If not, too late now if he isn't considered able to make decisions.

Cassie, I am confused by your question as you also had mentioned that you already have durable Power of Attorney for your husband.

Do you mean when should should start using the Power of Attorney?