I have similar nightsweat problems, so I did something close to this once: www.wikihow.com/Clean-a-Bed-with-Baking-Soda

If you Google “clean mattress with baking soda” you’ll find a bunch of similar recipes. Lots suggest using essential oils, which I didn’t use.

The results were decent when I did it. Definitely de-funkified the mattress a bit, and removed some of the stains. It was hardly like new, but it was definitely better than before.