I'd give it a shot. You never know what will help unless you try it because we are all so different. I have a pool and love to swim in it and it does help me with pain and flexibility. You are bouyant in the water and that makes every movement easier, too.
Swimming is considered a gentle exercise and gentle exercises really help with pain and fatigue from fibro. I also walk as a gentle exercise daily. Some like Yoga. I don't do Yoga because I wouldn't be able to get off the floor!