See if this article answers your questions.
https://pensionfund.org/uploads/Housing-Allowance-Information-for-Retired-Ministers.pdf
I would start with these guides as well.
https://www.ecfa.org/FileAccess.aspx?file=2020MinTaxes&source=NPO
One interesting question is why you no longer hold credentials. You must be a "retired minister" to use the exclusion on your pension or annuity. Depending on how, when and why you lost your credentials, you might not be a "retired minister" as defined by your denomination. That is something you would have to review with your church. I don't see any specific rules in the IRS documents that discuss this situation, they just say "retired minister."
Also, it's important to be aware that the tax-free housing allowance treatment is only allowed if your retirement account is sponsored by your church or denomination. If you were to do a rollover to a personal IRA (for example), then your withdrawals would not qualify even if you are considered a retired minister.