Pic would be nice.
But I seriously doubt if it's dying.
Leathers are notorious corals for sulking (for want of a better word) If stressed they close up and contort, this can last for days sometimes weeks. They eventually come back as vigorous and as vibrant as ever, mines done it about 4 times already. Watch out as they will secrete a mucus which is full of nasty chemicals which if it lands on other corals can damage them. Use a meat/turkey baster to suck up the white film it secretes. (a form of clensing itself)
Regards
BigC