I regularly get muscle knots—usually in my back but sometimes in my arms or legs. When I get the knots massaged and the knots release, I get a baseball-sized lump over the place the knot was. It feels pretty sore but almost a good sore, like it’s achy but feels a lot better than it did before. The swelling usually subsides within 24 hours but the spot stays achy for a few days. I’m wondering if this is related to fibromyalgia.