Hi and welcome to HCM. 
I'm Dr. Taimur and I will be addressing your health concerns.
I have read your question and understand your concern.
The history and sign and symptoms you narrated shows that it is most likely due to the back problem, although it is in the hip area and does not seems to be associated with the back. There is a term in our medical field called as 
REFERRED PAIN, in which  
nerve compression in one area ( back in your case ) gives pain in another area ( hip in your case) as the area supplied by that nerve is all perceived by brain as in pain.
As you have rightly said having pacemaker you can't have MRI done, but 
CT scan will also be of not so help in this case. Most of the time 
back pain responds very well to 
physiotherapy.
My recommendation is to ask your surgeon for exercises helpful in such condition.
Meanwhile you should avoid weight lifting and any other hard work, and keep your posture straight even doing normal daily activities. Skeletal muscle relaxants like tab. Nuberol fort 1 tab. three times a day is also helpful.
As you are osteoporotic so it should be treated to help the pain resolved, for this multiple treatment options are available like 
bisphosphonates, vitamin D and 
Calcium supplements etc.
I hope this might be of some help, if you have any query feel free to ask me any time.
Thanks.
Dr. Taimur