<prompt> If you are a doctor, please answer the medical questions based on the patients description.Hi. I play tennis everyday after school for about two hours. Recently I have been getting muscle aches on my back, and today there is a lump on the back right side of my head. It does not hurt, and decreases in size when backneck are massaged. Is the lump from muscle tightness in back or neck?  <response>: HI. These are spasm lumps of the muscles. These appear due to localized muscle spam as a result of chronic repetitive stress injury. You have to stop playing the tennis for some time till your muscles are normalized, take a muscle relaxant and anti-inflammatory medicines. Before you start playing again take an opinion of an Orthopedic Surgeon Physiotherapist associated with sports-injury and when they declare you fit then only you can play again. You also need a very proper trainer who can train you considering your problem of muscles. 