Small Child, Very Irritable, Keeps Crying, Stubborn, Gets Bullied By Other Children. Suggestions?

Hi, I have 3 yrs old daughter. For the past one and half yr, she has been really very cranky, irritable and tough to handle. Instead of asking, she cries for something and cannot listen to no . She keeps getting irritated without any reason. We both are working, so she goes to play school, then to day care and then I pick her up by late evening. Also in school, she doesnot mingle with kids, doesnot participate and gets easiy hit by kids younger than her. Pls advs what to do?