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Consult a physician first. But, please don’t look for any medical advice in this forum.

Good Luck...!!!

Well in that area you have a ball joint. Perhaps if you slept on it awkwardly, you may have applied enough pressure to the muscle or tendons that the muscles have tightened or the tendons have swollen. I'd try to mive your leg in a circular motion to find out the focus area. Then try to slowly and cautiously stretch that area. If it is swollen tendons then you need to stay off your feet for a while and maybe ice it or take ibuprofen. But try stew hung first.

It may be Hemorrhoids!

Consult a doctor immediately!