I started having a pain back in January after climbing stairs while carrying a book bag.  The pain occurred upon sitting.  It was a weird pressure that begin at the base of the back of my head and then traveled down my spinal column and into my hips.  When it started it felt like pressure, but a minute or so later it had built into a strong severe pressing pain.  It occurs off and on (not every time I climb stairs, not always when lifting something) and it happened again this morning right after I sat down in the car.
Hello, Thanks for your query. It seems that your wrong body posture; inadequate exercise and reduced muscle tone is taking a toll on your back. For pain to go, it takes not only rest (on a comfortable bed) but also avoidance of particular positions (during work, rest or recreation). During the day don't sit in one position for more than an hour and take frequent stretch breaks. Do not bend forward to lift things up, bend the knees and hips for that. Also discontinue any strenuous activity or exercises for some time. I suggest you to try back strengthening exercises by extension of the back muscles which can be taught by your Physiotherapist. This will help to relieve the possible muscle spasm which causes the pain do hope that you have found something helpful, and I will be glad to answer any further query. Take care