It may well be muscle knots. Muscles "knots" are areas where the muscle is stressed and has tightened or even swelled to the point of being uncomfortable. Really, they can feel like big bumps or even feel crunchy until pressure. They are semi- hard to hard and sore. So, it sounds like a prefect description. Chances are, if they are in your upper back, they are being caused by posture issues. Try sitting up straighter, standing straighter (be very careful, when standing, to align your chest. Many people stand with their lower back arched forwards slightly, tilting their chest back. That's bad.) Keep your shoulders back and don't hang your head. They could also be caused by neck/ back strain while working on a computer. Try standing and stretching more when doing this. If you are a female, try wearing a better supportive bra. If not, ignore that.