It is difficult to assess with your description, but if this is muscular, it seems you have strained your groin or hip muscle.
This could have happened by over exterting yourself or lifting with bad form. If this pain is affecting your daliy activities (like standing/walking) see your doctor. Your doctor can prescribe some medicines that can relax the muscles and assess if warm or cold compress will help.
Do not ignore pain that is intolerable or affects your daily activities. Your body is telling you something is wrong - see a doctor.