DNA testing is commom and pakistan has dozens of great labs that do it. I don't have any idea why you can't find one, it should be as easy as asking your local doctor to do it, and he sends a sample off to a local lab.
There are also official test centers used for immigration issues, but you may be able to use them also.
now some religious leaders there are fighting the use of DNA for paterinty testing
Pakistan Immigration DNA Testing