Changing Apple ID Causing Problems

(This could also be cross-posted to iCloud and anything else that involves the use of the Apple ID)

My long-time ISP has gone belly up, so I've lost my email address. Thus, I'm going around changing accounts and informing correspondents of my new address. I changed my Apple ID a couple of days ago to my new address and set a new password. Since then I have been having all sorts of problems with such things as iTunes, the App Store, and iCloud, where my Apple ID and password are requested/required to proceed. In most cases, the standard Apple ID + Password dialog or just the password dialog (with Apple ID already set and unchangeable) pops up. In most cases, it seems that my new Apple ID (i.e., new email address) has not been propagated to other places in the Apple ID "infrastructure". Where a dialog shows the old Apple ID, I have tried both old and new password to no avail. Also, I only just read and realized that my iTune/App Store purchases are tied to my old Apple ID, which is not longer valid. In addition, iCloud (which I, perhaps unwisely, set up with my Apple ID for access) will not grant me access using either my old or new Apple ID. Yikes! (Not really the words I've been using.)

Can someone lead me out of the swamp?

Thanks,

dds