Any idea what this is?

I'm 15 weeks pregnant and unbareably itchy. During the day it's usually manageable but come nighttime I'm up all night itching. I've tried Benadryl it doesn't do much. I've been to the dr and ER and neither would do anything besides say take Benadryl. I'm at wits end with this. It's also on my sides thighs and butt.