Since baby has arrived dog seems stresseds

I have a 4 week old baby girl, and a 1 year old chihuahua. I am a single mum So have tried to juggle showing the dog some attention inbetween carng for my new baby. 

the dog is a loving and affectionate well behaved chihuahua. But recently has cheweds the fur off her back legs, started scratching at doors to get into rooms she never used to. And most recently crying for no reason. Even when im playing fetch with her shes collecting and returning the toy but whimpering as she is playing. I dont know what to do?!