There is a lot that goes into answering your question, but I'll stick to the main points to keep this short. The shortest answer is yes, the weed is probably making it hurt less, both through medicinal properties (anti-inflammatory, pain reliever, etc) and distraction (you are high, and not as focused on the pain). However, it could be coincidence, or placebo as well.
You also have to consider the strain. Some strains are great for pain relief (white rhino was actually bred for it), others do nothing for it. Some relax your muscles (generally indicas), while others are anti-inflammatory (certain sativas, and this works for retinal pressure as well as muscle inflammation, which is why sativas help glaucoma). The right cross-bred strain can be perfect, or useless, for your particular problems.
Remember that even in clubs, a strain name is wrong as often as it is right. If what you smoked actually was Pandora's Box, then you can trace its genetics to its roots to figure out how/why it will effect you. This is the best way to find the right strain if you want to really use cannabis as a medicine. In the case of Pandora's Box, for example, it is a cross between JTR (Jack the Ripper) and Space Queen. JTR is Jack's Cleaner crossed with Space Queen, and Space Queen is Romulan crossed with Cinderella 99. I'll let you investigate from there if you want to follow the genetic family tree all the way back and see how/why that strain does what it does, but the theme in this case is that it is mostly Jack Herer strains crossed with Space Queen strains at different points. So, if you investigate the effects of those strains, you will get a good picture of the effects of Pandora's Box. That is generally how you research a strain. Good luck!