WordNet sense 1 (agitation resulting from active worry):

fret, stew, sweat, swither

WordNet sense 2 (the froth produced by soaps or detergents):

soapsuds, suds

WordNet sense 3 (beat severely with a whip or rod):

flog, lash, slash, strap, trounce, welt, whip

WordNet sense 4 (rub soap all over, usually with the purpose of cleaning):

soap