hii, very random lol but best way to clean a mattress and to get the stains off i’m unsure what it is but one of my guesses would be sick. thank you x

Try a mixture of baking soda and water (make it into a paste) and let it sit in this stains. This should pull some of the stuff out! Or try Oxy Baby spray product. It’s pretty good at getting stains out. For both just let sit for 10-30 minutes and then scrub with water