Weird blood pressure

Tomorrow I’ll be 34 weeks, my doctor has sent me to the hospital twice because of high BP, and they’re now having me monitor it at home and seeing me once a week. I’ve had no issues checking it, but today I got a couple high readings in my right arm, just now it was 152/101 but 143/86 in my left arm. And this was after resting, I haven’t done anything today but take a shower earlier this morning. My doctor said to call if it’s over 160/110, my mom seems to be pretty concerned and wants me to call, I’m really not understanding why it’s high in one arm and not so high on the other. I really just don’t want to be sent back to the hospital for them to tell me I’m fine once again. Any ideas?