It sounds like your sciatic nerve when you gain weight it starts to hurt on the right side kinda by your butt but right above it. Drink water there isn't much you can do. It will come and go. But after pregnancy it should completely go away.
Sounds like round ligament pain.
Have you dranked water today??? You could be just dehydrated?? If you have any cramps and bleeding with the pain call your doc. Other than that you should be okay, sorry your in pain but it will get better