back irritation

Hi, I'm currently abroad so I have to write in English. In the last two weeks, after working in a physical job and lifting heavy loads, I'm experiencing a some sort of "burn" sensation, appearing in waves, very disturbing, in my upper left side of my back. After a little rest it improved but I can still feel it and I can point the source of it is in the left side of the spinal cord. I know I must have it checked, but from your experience, what are the possibilities? could it be cancer? Thanks in advance