has anyone else experienced extreme lower back pain?

I've been experiencing it for about 6 weeks now I'm currently 16 weeks pregnant.

it was so bad I couldn't even walk to the bathroom last night I had to crawl.

it's not only in my lower back but also the back of my thighs. it's getting really hard to do my job which consists of walking 5- 10 miles a day and standing for 8 hours straight. I've talked to my obgyn but he really didn't say anything about it. my mom thinks it's my siatic nerve.