S.-
First of all, good career choice... I have worked in forensics. On to the tantrums. Stand your ground. I know that talking to a 2 year old is hard (my oldest is 2 1/2) but when she isn't freaking out, ask her why she's been such a naughty girl lately and tell her that you really don't like it when she's that way, you like the sweet little girl that she used to be. Then go on to tell her that when she's naughty like that (give examples: the screaming, the hitting, etc.) that she is going to be put in a time out in her room and the longer that she misbehaves (screaming after you put her in the room) the longer her time out will be. {I've always been told 1 minute for their age.} The next time that she misbehaves, and you have to put her in her room, when she finally stops screaming, start the 2 minute time out. After she is done being punished, calmly talk to her and explain to her why she was punished, ask for an apology, give her a hug, tell her that you love her and ask her not to do it again. Guaranteed, she will do it again, but if you are consistent, the times should become fewer and further between until you have your little girl back. I started this with my 2 1/2 year old and although he still has meltdowns, the are much, much fewer. Good luck.