Giant Cell Arteritis

I was diagnosed with Systemic Lupus about 30 years ago at 37. It’s been pretty mild but for the last 6 weeks I’ve been really sick. My current Rheumatologist thinks it’s one of the PMR autoimmune diseases called Giant Cell Arteritis. My inflammatory markers are through the roof; CRP 266 & ESR 78. Still waiting for all the test results to come in but in the meantime steroid injection has not helped much. I’m really worried about my eyes; have had problems losing vision especially in the last 6 months. Anyone can share more about GCA? I’ve been reading up on it but would appreciate hearing experiences from other patients. Thank you.