separation anxiety?

so, lately brooklin has been freaking out when we put her to bed. she used to go down just fine with no problems at all. she knew it was bedtime and she would go right to sleep. now she just starts wailing the minute i leave the room. the last couple of nights i've gone back in her room to calm her down and she has gotten herself so worked up that she's sweating, and the only way i can get her to settle down is by rocking with her. i really don't want her to get into the habit of being rocked to sleep, but at the same time i don't really know what else to do and i feel so bad because she is literally screaming. i've also noticed that a lot of times when i put her down on the floor in the living room to play with her toys so that i can do the dishes or whatever, she whines and cries. it's like she's moving backwards. i feel like we finally got to a point where i could get stuff done during the day and she was going to sleep really well at night, and things were going really great. now she's decided to freak out. is she starting the whole separation anxiety thing? or is she just not feeling well? i keep checking for teeth and checking her temperature, but i don't think she's teething. maybe she just really does miss me that much. i dunno.