Yes there's no problem with mixing apple cider vinegar with Epsom salt and in fact it's known to be a good foot bath for soothing sore feet.
You can also make a detox bath to soak in to detox your body.
To make a detox bath with apple cider vinegar take a quart size jar and dissolve some Epsom Salt, Salt and baking soda in some boiling hot water and then set the jar aside while you fill your tub with warm/hot water and then add some apple cider vinegar to the bath water and then pour the jar with the salt and Epsom salt into the bath water.
Once that's done then if you want too and have some add about 3 to 4 drops of essential oils to the bath and then soak in it for however long you want too.
The detox bath will pull toxins from your body and make you healthier.