could it be that she is just really overtired so constantly fighting sleep and possibly not napping enough during the day? even now at 21 months DD still sleeps like 2-3hrs during the day. Perhaps if you could spend a few days just constantly watching her tired times, and if there's some sort of pattern, maybe trying to put her down even 30 minutes earlier? It may help with the screamy crankiness.
Does she like you singing to her? I found when DD was going through a stage of this, i'd sing her a song (Mockingbird) and she loved it. even if she was screaming id still keep singing to her and usually after a little bit she'd calm down. I also used to sing it at other times during the day so it wasnt just a bed time song.