I will soon be a licensed massage therapist & they are worth the money! but in a pinch here are a couple of things you can do
1) take a bath towel roll & it up (or take a tennis ball)place it on the floor, lay on you back with it between your shoulders & kinda roll around on it till it is in the place that is ailing you & work that area
2) lay prone on the floor & let someone gently take a rolling pin & knead your back with it. you will be suprised it feels great!
most importantly watch your posture. If your shoulders are slumped forward & your pect muscles tight the rhomboids (muscles between your shoulders) Will realy suffer for it. You will need to stretch your chest muscles out. Put your hands behind your head step into a door way with your elbow held in place by the door jam & ease into a nice long stretch. Switch arms & do the same with the other.
good luck