exasperation

discomfort, fleabite, pinprick

affront, insult, offense (or offence)

upset, worry

affliction, albatross, burden, cross, curse, menace, millstone, plague, sore

anxiety, plight, predicament, tribulation, trouble

hang-up, pet peeve, problem

annoyer, disturber, harasser, mischief, offender

pandora's box

agitation, discomfort, displeasure, distress, disturbance, upset

irritability, irritableness, peeve, perturbation, pet, pique, resentment, snappishness, trouble

anger, angriness, chafe, dander, dudgeon, gall, huff, indignation, irateness, ire, outrage, umbrage