hotchaitogo,
From what you are describing, it should be pretty evident on a thorough hip examination, if one was done. Bursitis does not cause significant decrease in the passive range of motion of the hip. It might cause discomfort, especially if the patient does active range of motion.
But, with passive range of motion, you take out the patient having to actively move the joint, so the pain should be less. If the range of motion is significantly different, then there is something going on in the joint itself, usually.
You should be seeing at least an orthopedic surgeon. If you are already seeing an orthopedic surgeon, and he/she is still not taking you seriously, then look for another surgeon. One that has subspeciality training in hip surgery. That may be a total joint surgeon, but these surgeons do other things with the hip joint other than just replacements. And they have the extra training to be able to pick up the subtle problems going on around the hip joint.
Studies for problems around the hip, usually start off with a set of good plain x-rays, which may include an AP (of the whole pelvis), frogleg lateral, cross table lateral, and weight bearing films. A bone scan may be ordered if there is concern about inflammation around the joint. An MRI looks at the soft tissues best. A CT scan is best for looking at the bones and joint, and how they relate to each other. Some surgeons also use the ultrasound, but the physician reading the ultrasound has to be specially training in musculoskeletal pathology.
So, if your doctor is not taking you seriously and has not done a thorough exam, ask for a referral. You sometimes have to be proactive and look out for your own health care. Good luck.