Dean, you need to get checked for Giant Cell Arteritis, GCA for short. Along with the temporal arterial biopsy, ultrasound arterial scanning is increasingly relied upon. Check out the work of Prof. B. Dasgupta. He is the world authority. If GCA is diagnosed, please do all you can to get the steroid treatment started asap. I've been down this rocky road myself & your post has a familiar ring to it. Time is of the essence.
                                                                  Every good wish,
                                                                                             Nigel.