Icky metallic taste wakes me up.

I am 13 days post op. For the last 4 or 5 days,  I have been rudely awakend with a metallic taste.

What is it? How do I get rid of it?  And most importantly, how do I prevent it?

Sounds like ketosis;  that's your body burning off fat and the byproducts of this product are ash, etc. These byproducts are excreted through urine and your sweat and breath.  It'll go away eventually but it's a nasty taste.  Drink a lot of water to help flush these byproducts out of your body.

Sounds more like reflux to me....are you on a ppi?....(nexium, losec etc?)  

I agree with Ketosis.  The metallic taste is a common symptom of it.

Your body isn't getting enough instant energy (carbs), so it's feeding off of your fat stores for energy.  This is a good thing!!

To lessen the effects, drink more fluids to flush the ketones (byproduct of ketosis) out of your body faster.  This will probably go on for a couple more weeks.  You can google Ketosis to learn more.