Sprinkle baking soda over your entire mattress, let it sit for few minutes before vacuuming to get rid of any smells. Next, you will want to use a mixture of peroxide, dish soap and salt to get rid of stains from blood, sweat and urine.
How to whiten yellow shirt stains: Mix together 1 tbsp Dawn dish washing liquid, 2 tbsp hydrogen peroxide, and 2 tsp baking soda. Apply the mixture to the yellow area and scrub gently. Leave sit for two hours and launder as usual.