She may be under a lot of stress from work and might have took it out on others. Don't let that affect you when she yells at you... she might be having a hard time that you don't know of. Maybe talk to her about it. If she doesn't say anything, then just understand since she doesn't want to tell you her problems. If you want to help her, then maybe just make her day by doing things that she appreciates you doing.
I hope things get better <3