M.B.
I had this problem this summer. My son sleptwalked and peed in his bedroom. I didn't know about it for a few days, and hoo-boy was the stench unbearable!
I found good old fashioned baking soda worked wonders. Sprinkle it liberally on the carpet and let it sit for a bit before vacuuming it back up. I used my hands to sprinkle it about, crushing the chunks while distributing the soda. It's inexpensive, perfectly safe for pets and children, and won't result in an olfactory lasagna of conflicting odors.