C.B.
Sounds like you have PUPPPs. I had it (on my stomach, inside of thighs, behind my knees, around ankles, inside of elbows) when I was pregnant with my now 15 year old dd but I didn't get it until around 6 months. Back then my doctor would only let me use baking soda baths to help relieve the itching. I think I have read that it is safe to use Benadryl during pregnancy now but really you should always consult your doctor before using any kind of medication.
If it is PUPPPs that you have, it will not go away until you have the baby. That was the most miserable part of my pregnancy. I was so thankful I did not get it during my second pregnancy.