The wrong posture may be one reason but in my view, you are travelling more than desired so your issue is related to "REST".
You should take at least one hour rest after a travelling of 1/2 Hour then there will be no need of medication too.
Secondly, you should take a long rest like 7-10 days and then you will be better for one Year. However, the exercises related to back pain will be an added advantage for you. For the reason, here are some pics for your help from the link given below:
Low Back Pain Exercise Guide -OrthoInfo - AAOS