I got diagnosed with PUPPS and they told me to take one Zyrtec and one Zantac at the same time during the day and that helped a lot. Honestly my mom made me some homeopathic anti itch spray and it took the majority of it away! Try that!
I got the same thing and I'm 36 weeks. It started on the bottom of my belly last week and now the back of my arms and back of my knees are itchy. The doctor told me to use a benadryl cream. Our only stops the itch for a few hours but it will be away after you give birth.
Hopefully you aren't getting PUPPS! Olive oil seems to help, or dr. Teals makes a new bath and body oil that is super helpful!
Get some bio oil and cocoa butter lotion and put those on yur belly and boobs and butt twice a day
Your growing, the skin stretching is whats so ichy. Just keep applying that stretch mark cream :)