So sorry to hear about his problem, it sounds like he has had to deal with a lot these last few months.
There are several possibilities: Because of the left sided injury, we tend to overly compensate and put more strain on the side that was not injured (right side in his case) which can cause extra strain and put pressure on the right leg, including the hip.
As we age, most of us develop some osteoarthritis, wear and tear if you will, which your father probably has and it is being aggravated.
There could also be a small fracture in the hip area since the pain is so severe with standing, so it may not be a bad idea to get checked out and get a hip xray done just to make sure nothing more serious is going on.
For osteoarthritis the recommended treatment is Tylenol (if no liver problems) and if that does not help then medications like Ibuprofen (used with caustion due to possible kidney problems) physical therapy, chiropractor or acupuncture.
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