Dog Psychology 101

Perhaps someone can shed some light on a change in my dog's personality.
I have a Begian Sheepdog named Abby. She is about 11yrs old. Spayed.
Other pets: Buddy, neutered Rottie/Dal mix 9 yrs old.
Brutus, Yorkie/Pug mix, neutered 3 yrs old
Indy, full Chihuahua, female, 6 months, not spayed yet.
2 cats 9 & 12, males neutered.

Here is the problem:
Abby has always been an introvert. We got her as a puppy from the local pound. She is one of those that they always warn against adopting as she hid in the back of the kennel, refused to look at you and shivered. Took her anyway. LOL Well, she was probably 6 months old before she trusted us enough to come without cowering or hiding when we called her. She would at times lay by you as long as no attempt was made to interact with her. Well, over the years, she pretty much just existed although she was very happy to go for walks or car rides. When I got the other animals, she pretty much just accepted them like she had no choice. Never had much interactions with them as far as wanting to play or anything. Basically, she tolerated their presence and they were aware of it and left her alone. Well, about 3 months ago, she has done a 360 in personality. In the past, the only time she would get on the bed and seek company was during storms. Hates them. Even if she got up, she would get down as soon as the rottie mix joined in. Now you can't keep her off the bed as long as I am there. Doesn't matter who else. She sleeps next to my head. If I get up, she gets up. When I have to leave in the morning, she follows me to the door and wants to go with. I have to keep a squirt bottle next to the door to keep her away long enough to get out. She is constantly wanting to be petted. Nothing has changed in the household except the addition of the female chihuahua 6 months ago. Is it possible that she if feeling jealous of another female in the household? I can't think of anything else that could have brought on this change.