Memory seems to have a case of seperation anxiety, which I just discovered this weekend. This Thanksgiving, we're visiting our friends in another state for 3 days, and we cannot take Memory because 1) both my friend and her little brother are allergic to fur and 2) their mom has a major fear of dogs, and she is scared to death of Memory, even if she's only seen a picture of the poor girl. Well, thing is, we've never left Memory in another person's house, or by herself for more than a few hours. We usually take her everywhere with us. I do not want to leave her inside her kennel for 3 whole days, so we found a friend who was willing to take her in for a time. Memory has known her since she was a puppy, and doesn't have many problems with her. So as a test, we left Memory at her house for a day, or at least, that was the plan.
She was not aggressive towards her sitter, or her husband, or their greyhound. However, she would not leave her crate. When the sitter approached her inside her crate, she began to growl and when the sitter got too close, she started snarling, with her lips pulled back and teeth showing (this was all reported to me, since I wasn't there). So the sitter backed off, and tried to lure her out with food. Memory would do anything for fresh meat, but she took a couple sniffs, and even poked her head out, but ignored it. The sitter tried approaching again, but Memory snarled just like before. But when their dog walked over, she did nothing. I figured that it was because she was in a crate and might have felt cornered when people neared her, so I went over to get her out. The moment I opened the door, she leapt out and bounded over to me and licked and whined and nudged me and pulled her ears back. Well, she was out of her crate, so I left again (even though it near killed me, she looked so sad!).
So she was in a room and simply curled up by the couch and wouldn't play with toys or Nellie (the greyhound) or anything. And when the sitter walked into the room, Memory actually GOT UP and walked straight OUT of the room. I've told them she responds to commands such as "come" "sit" "stay" "no" and such, so they tell her to come over, but apparently she refuses. The sitter told me she seemed to have heard them because she perked up her ears and looked over, but didn't do anything. They tried different commands but she wouldn't. And when they tried to leash her to take her on a walk, she began to back up and snarl the moment they got near. According to their discription, she did not look like she was scared, but like she was trying to tell them to "back off" in an aggressive manner, because her tail was raised high and her fur was standing up. We ended up taking her back home before the day ended, and you should've seen her expression when me and my mom walked in! When she got home, she nearly knocked over my sister in excitement, and she was never that friendly with her before!
I probably won't end up going this Thanksgiving to my friend's, but I really need help with this. Another sitter isn't an option because she absolutely hates/fears strangers and won't have much to do with them. She has been socialized a ton and I am positive that she would never bite anyone, but her behavior is unsettling. I'm sorry for such a long story, but I'm worried, because we can't always stay with her 24/7! 
Help, please!
*As a note, Memory only used to suffer from SA when she was a puppy, but we got her out of it. Usually, we can keep her inside her crate or kennel and leave the house for a few hours, and she'll be fine.