excruciating

adj

1. Causing great pain or anguish, agonizing

   “Sagan faced an excruciating dilemma: Should he remain true to his naturalistic philosophy and reject the marrow graft as something acquired by immoral means? Or should he agree to undergo the medical treatment in hope of saving his life”

2. Exceedingly intense; extreme

   “When he at last opened his eyes, he was conscious of nothing but an excruciating pain through his temples. He was vaguely aware of unfamiliar surroundings.”