Synonyms for Agonize:

n.

fret, upset yourself, hardly dare (to) breathe, have a lot on your mind, panic, fear, dread. squirm, repetition, writhe, turn, toss. agonize (noun)
agonise.
anguish (noun)
worry, writhe, struggle.

v.

lament (verb)
moan, bewail, groan, decry, sigh, grieve, snuffle, whine, weep, clamor, lament, whimper, mourn, bemoan, sniffle, wail, ululate, cry, long.
pain (verb)
discomfort, torment, sore, sting, rack, cramp, stitch, crick, smart, chafe, throe, ache, inflame, hurt, torture, wrench, irritate, afflict, suffer, throb, distress, anguish, pain.
punish (verb)
correct, sentence, lambaste, penalize, incarcerate, chastise, persecute, confine, judge, chasten, reprise, avenge, execute, discipline, try, Keelhaul, fine, burden, pillory, punish, crucify, castigate, imprison.
suffer or cause another to suffer (verb)
hurt, afflict, crucify, pain, writhe, lament, rack, excruciate, torture, worry, try, struggle, torment, distress, squirm.

Other synonyms:

excruciate, fret, dread. scourge, writhe. squirm, worry, smite. toss. strike. turn. Other relevant words:
repetition, attack, fret, excruciate, smite, fear, strike, writhe, turn, curse, panic, worry, scourge, agonise, squirm, toss, struggle, dread, plague.