Sulfa drugs may be very different thing.
Get mineral water rich in magnesium, and drink it.
If you can tolerate it, try small amount of epsom salt.
If you can tolerate small amount of epsom salt, try more the next day.
Increase amount every day until you are sure you can tolerate 1 - 2 tbsp per day. (That is the amount of Epsom Salt
you are suppose to take during flush)