Maybe get a tasty treat for her to gnaw on. I know my dog loves knuckles and bully sticks. Make sure to walk her and give lots of love and attention. Another idea... maybe there is something physically wrong... take the dog to the vet and have it checked out. There could be more going on than meets the eye.
She's probably just mourning, she will be fine after awhile, you could ask your brother to come over regularly to reduce the stress on her.
That's actually very true, I'll make her an appointment. It's just weird cause she started acting like this when he left last week... I took her for a car ride which she loves and she just sat there.
If the dog was with your brother for 6 years, she won't forget him in just a few days, itll probably take a few weeks, maybe a month. Right now the dog probably feels abandoned, you need to show her that you are there for her and want her to be happy.