BSM taken internally, I presume?

Would be pretty messy applied externally!!!

For external use, MOM [milk of magnesia] as a replacement for other skin treatments and/or the alkalising bath with ES [Epsom Salts] and H202 Hydrogen peroxide] are helpful.

Some also benefit from alternating use of magnesium containing stuff on the skin [alkaline] with the acidic ACV [Apple Cider Vinegar]

Many more options possible for emergency care of the rash issue in past threads at this forum.

Long, term, diet and lifestyle changes needed. Those are addressed here also.

Usually, one's own version of this forum's alkalising drink while one transitions to better quality foods as well.

More info on all of these including detail about how others used them and the outcome can be found by using the search feature in this forum.

Di