Confused, down & tired

After I left the house, my mom & I made up (I’m 17) & she had been the sweetest the days following. She’d call me honey, she’d tell me “I love you” if I made a mistake she wouldn’t get really mad, we had a loving relationship but now it’s like the devil’s gotten into her. I got home & she started bitching at me, she almost hit me with a broom because I answered my stepdad’s phone call who was asking for $20 that he accidentally gave her & was supposed to give to someone he owes. It can’t be because she’s had a bad day. All she does is stay in bed & go out if she feels like it cause none of the us are home. She has the balance of being in an empty home half the day & with all of us the other half. I don’t get her. Sometimes she’s so nurturing & out of nowhere she’s the devil 😞 it sucks so much.