hmm.. well nobody know for sure. but here is my theory.
the supreme court which was sacked by the previous ruler (musharraf, who was a military dictator) was reinstated. this judiciary has decided that the criminal and corruption cases involving the Zardari and co should be reopened. these cases were previously closed by musharraf (as a compromise deal with Benazir bhutto, the wife of zardari). The cases involve billions of dollars of money laundering from pakistan to England, Switzerland. the govt is under pressure as it has lost all public support and basically has no legitimacy at all. therefore they have started creating problems, in order to provide them an excuse to stay much longer.
on the other side the army is fighting the ttp in north west pakistan. It cannot intervene. then u have US drones attacking alqaeda people within pakistani borders. Meanwhile US agencies have infiltrated into pakistan's nuclear assets as they want to denuclearize pakistan.
zero governance + corruption at all levels + terrorism + US intervention = total mess = what is happening in pakistan.