this struck me because my DH is also a pastor. If he is Bipolar, it's not normal bipolar, it would have to be rapid cycling, otherwise it's not common to experience manic and depressive phases within the same day or week. Normally, only a few cycles a year tops with regular bipolar.
I would wonder if there is a link between the steroid treatments. Cortisone mimics cortisol, the stress hormone. Too much or too little cortisol in the system can cause major problems, some of which could manifest in anger and anxiety. I'd say see if your husband would agree to having his cortisol levels checked in addition to seeing a psychiatrist.
Also, if he is threatening (or contemplating) suicide, please get him in to see someone. If he won't go, you can (on the basis of his expressing a desire to harm himself) have him forcibly taken. It's not a great option, but it's much better than dead husband. We tried to have my husband forcibly committed at his worst, fortunately, he wasn't expressing suicidal thoughts, so they wouldn't take him, and in the end, we were able to get him to a hospital where he agreed to be admitted.
Also, if he is bipolar prozac probably won't help by itself, and actually, it can bring on manias. So I'd get him off that pronto until you get it sorted out.
Do consider seeing a endocrinologist and checking those cortisol levels. With all his anger, it sounds like a plausible issue giving his medication change. He might also be more willing to go that route at first than a Psychiatrist. And also, if you can give him a little massage with rescue remedy cream, that could help. Or take a look at the Bach Floral Remedies (google search will get you there) if you can find one that sounds like him, I say slip it into his drinks as often as you need. When my husband was out of control, I did everything I could to see if I could bring him back before we took him to the hospital.