Hi Alaska,
I can sympathize with your problem. I had a cat that had some medical problems, and would pee on my bed. This is a sure-fire fixer. (At least it is for me, 100%).
Oreck (The vacuum company) makes a product called "Enzyme Odor Remover". If there isn't a store near you, you can order it online. First of all, get some warm water, and wet the area as well as you can. I actually had a sopping wet rag that I used. Then, with a thick towel, blot the area really well. I actually stood on the towel on the bed. Then spray the area really well with the Enzyme product. Do this in the morning, and leave it stand for an hour or two. Then put another towel down over the spot (I double the towel), and make the bed as usual. Well, not as usual, you should probably get a water-proof mattress pad. The next time you change the sheets, just remove the towel. You shouldn't be able to see a spot, nor should you have ANY odor of pee.
The Oreck Enzyme Remover is the ONLY product I have found that completely removes the odor and the stain. To work best, the area needs to be damp, hence the water first. But the water also dilutes the stain. Good luck!