Ro do this kind of testing is very difficult and the conditions required have to be just so. It's too hard. They would also have to have the live worms to test on.
There are other meds out there that can treat pinworms but those are the most common ones we named. 3 Days of Vermox and or Albenza is not enough for the infection that you describe having.
Also your pills could be weak or just plain fake.
The fact that when you take meds the itching gets worse is good and bad. It's good because it mean it's doing something but bad because it means they aren't necessarily dying but are more active, scattering, trying to come out etc.
You will have to wait at least a few weeks before trying the correct protocol for pinworms. You can find that here on curezone.
You also never mentioned (to my knowledge) if you have any animals or are exposed to children (certain ones in particular) on a regular basis.