PMS + A SCREAMING 3 YEAR OLD = AHHHH!!!!!

I do not know what has gotten into my 3 year old ! He has become a hard to handle child ! I swear he is 3 going on 16 . He screams all the time , whines and tells me and my husband to " shut up " . I am ready to call in supernanny ! And yes , we desipline him . Nothing is working ! Help ! I feel like I am failing as a Mom :( . Thank God the one year old is good ( hopefully he will stay that way ) The two are like night and day . The bad thing is they already fight . I need a vacation !