Go for it! I have only done very short versions twice: once from O Cebreiro and once from just after Sarria. Fibro varies a lot from person to person, of course, and flare up triggers vary a lot too... but I admit walking was easier than dealing with the fibro at work and 'normal' daily life in a busy big city. I carried only basics, as pretty much everyone does (sleeping bag, change of clothes, small towel, light flip flops), and managed the weight ok. Some days were better than others and sleeping in albergues did not make for the most restful nights but then, I often have poor rest in my own comfy bed at home anyway. Pacing yourself as much as you can, not pushing too much beyond what you think is reasonable for your body and other usual coping strategies for the condition will hopefully get you through. Best of luck!