Weimer/lab mix help?

We've had a weimeraner/chocolate lab mix for about a year now, the dog was a rescue and was previously beaten, and i believe they lied about the dogs age, as she has grey hairs in her face and they said she was only four. When we got her at first she would bark at people she didnt know, however she would stop when we told her to stop barking, now she has started barking randomly for no reason at nothing, barking endlessly at people she's seen multitudes of times, and has been getting very protective and aggressive, snapping at people and charging at them when they come near her, which is not like her since she was normally a very docile dog. Was wondering if anyone here could help out and try to figure out why, whether its the breed or what. She has been very well taken care of since we got her, no abuse, always had food and water, given plenty of attention and taken for walks and such.