I have no time
To make this very clear right in the beginning: there is no drug to cure back problems, and taking drugs against back problems is not back care but rather the lack of it.
But this is how the world goes, so we will give some advice for all our far too many I-have-no-timers.
Generally speaking non-steroid anti-inflammatory drugs, so called NSAID’s, have been established in the last decades as world’s preferred defense against back pain. They have few side effects, are mostly well tolerated, cheap and easily available over the counter. As the name suggests, they fight inflammations, which in most cases are part of any back pain, and at the same time are real painkillers. Ibuprofen is among the best ones against back pain, if you want something even stronger you can go for diclofenac.
But keep in mind: even very time tested drugs like NSAID’s are not meant to be taken over a longer period of time. So if your back does not stop hurting after a few days, you must see a doctor. If you do not, your back will force you to do so sooner or later, and then you will have time. Guaranteed.