OK, why is my iPhone 5 now a super electromagnet?
I know you said Please don't tell me it is the speaker magnet, but I have opened a number of iPhone 5 phones and this is the only magnetic part within the whole iPhone 5 - so it can't be anything else.

And when you say I assure you it is not the speaker magnet, how do you know? What evidence do you have?

The reality is it can't be anything else. If you check this iPhone 5 teardown you'll see everything that's inside your iPhone 5. While some parts are magnetic in the sense that they will stick to a magnet, the only magnetic source is the speaker magnet. 

Also, because the iPhone comes with a compass, it has been very carefully designed so that any magnetic fields do not interfere with that. In other words, Apple hasn't placed any unnecessary magnets in the phone except for the speaker magnet (which can't be avoided).

Finally, while I'm no medical expert, the concern around mobile phones has always been around the electrical signals they require to operate, not about magnets. If you're concerned you can use an appropriate case (if you haven't already got one) and/or use a bluetooth earpiece/headset for calls.