There are number of bursae around the hip joint that can give rise to symptoms. The most common one is the trochanteric bursa. The bursa contains a small amount of fluid to allow the muscle to glide over each other with minimal friction. Most cases of trochanteric bursitis come on gradually over a period of time with no underlying cause or injury. Sometimes they can be change routine activities as well as a Different seating position in a new car or new settee.
Patients usually present with pain on the outer aspect of the hip joint, which radiates down the outer aspect of the thigh, this is made worse by sitting for long periods particularly in a low seat and driving. The pain is usually a dull ache most of time and the times sharp severe pain like toothache. Sleep can be disturbed and lying on the affected side it's painful and is avoided.
Treatment it's busy to avoid activities which exacerbate the symptoms, use of appropriate analgesic anti-inflammatory medication and physical therapy to help stretch out any tight muscles and strengthen others. Further management may require steroid injections which can help symptoms for many months or permanently in some cases. Surgery is hardly ever required and the outcome is unpredictable.
More information: http://orthoinfo.aaos.org/topic.cfm?topic=A00409