My husband and I were having sex doggie style. He thrusted into me really deeply and I arched back at the same time. I felt a sharp pain in my left hip. It went away but there is still a dull pain. Is this something serious, or just a little strain or something? Thanks

Chances are you might have pulled/strained a muscle in that area. Keep off it as much as you can and keep an eye on it. If it doesn't go away in a day or two see a doctor.

I suspect it's a strain - but as suggested, keep an eye on it and if it continues see a doctor. Strains can take a few days to get better.

While this happened during sex, it really isn't a sexuality question.

Muscle tear, tendon inflammation, bursitis, etc..

Good general rule is the RICE method... rest, ice, compress, elevate...

If dull pain persists, get it checked out. I found out, after months of dull pain in my shoulder, that id partly dislocated it after a motorcycle accident. Oops. The fix was PT and a few shots. Of the needle kind, not the bar kind.