When you sit in same posture for longer hours, your core muscles get strained. These are the muscles which support your spine when you maintain erect posture. If these muscles get weakened then they won't support spine and ultimately you land up into back pain.
To get rid of back pain you should start core muscle strengthening exercises. But along with this you should start Stretching as well. Apply ice pack on painful area after Exercises but make sure that you don't apply it for more than 2-3 minutes on same area.
Spa induces relaxation. It doesn't increase muscle strength which is actually required to get rid of Back Pain. If Massage is done in proper direction aiding lymphatic drainage then only it's useful or else it might increase pain.