That's a fair bit of strain on the hips for a new pair really. While I agree the waist should be tight and its too early to make a decision, it doesn't mean the rest of top block can adapt to the same same amount of stretch.
Give it a few more days but tbh... The pain is not worth it.
If the stretch out that much a size bigger would be definitely baggy at the end. I mean, I'm not dying by wearing them, but they are definitely my more uncomfrotable pir of jeans, they seem too far away from second skin haha