Whiner

Noun

 * 1) One who whines about perceived problems; a complainer
 * I never realized that Felicia was such a whiner, but she complained steadily about various minor discomforts for the entire road trip. 

Thesaurus
bellyacher, complainant, complainer, crab, crank, croaker, faultfinder, frondeur, griper, grouch, grouser, growler, grumbler, kicker, kvetch, malcontent, murmurer, mutterer, querulous person, reactionary, reactionist, rebel, sorehead

Synonyms

 * bellyacher
 * crybaby
 * whinger
 * See also Thesaurus:complainer