I remember those early weeks being such an odd mix of excitement and random aches. Hip or buttock pain on one side at 10 weeks is usually from everything starting to loosen and stretch. The round ligaments and sciatic nerve can get irritated as your uterus grows and your posture changes.
What helped me was being mindful of how I sat and stood. Crossing my legs or slouching on the couch would make it worse, so I propped myself up with pillows and tried to keep my knees level with my hips. Gentle stretching, like figure‑4 piriformis stretches, and prenatal yoga eased the tension. A warm bath or a heating pad on a low setting on my hip at night was heaven. On really bad days I wore a soft maternity support band to take some of the pressure off. And of course, sleeping with a pillow between my knees while lying on my left side helped keep my hips aligned.
If the pain shoots down your leg, gets very sharp, or is accompanied by other worrying symptoms, definitely mention it at your next visit or call your midwife for reassurance. Most of the time it’s just your body adjusting, and a bit of rest and stretching goes a long way.