Look in a large supermarket, in the cleaning products aisle. It can be in an aerosol can, it’s a foam. If you can’t find it, look for car upholstery cleaner foam.
See if you can find febreeze anti-bacterial spray, you can use on fabrics.
I wouldn’t personally use the dettol surface spray bcos that’s something you have to wipe off after you use it, can’t be done on fabrics.
Check Ikea for mattress protectors and use one from now on, under the bedsheet that you sleep on top of.