Hip pain?

Hi guys... so for the last 2 weeks I've occasionally noticed a sudden sharp pain in my right hip (twice when laying down in bed and three times at work simply sitting down). It's more lower back hip area than the sides. I've seen some articles say it's due to weight gain but I haven't gained a pound thus far. (I'm almost 20 weeks and I am down 16lbs from my pre-pregnancy weight). I just want to know if anyone else has experienced this with their first born.