Self-massage using a foam roller or a spikey ball feels good, but it can also alleviate pain and prevent further injuries. But which is more effective?   Problem: Generalised pain or tightness; stretching fascia, or connective tissue. Solution: Foam roller “Foam rollers are great for stretching fascia, or connective tissue in the body,” says physiotherapist Alex Lakos (sboydpt.com.au.)   Problem:  Sharp pain, like a knot. Solution: Spiky ball.    “When…