Medicine to treat pinworms can be purchased in Mexico at low cost with NO prescription. These are international quality brands. Mitafar, mebendazol, Ivermectin, albendazol. Fly into Mexico City and walk to any pharmacy. Stay at the Hostel Mundo Joven Catedral which is decent and cheap.
Apply Noxema or Vaseline to your bottom to stop the itching. Place a cheap sandwich baggie on your hand to scoop up the Vaseline and apply. Use a new baggie each time. Wear disposal pants like Depends if you can.
You can take albendazol 400 mg twice a day for several months.
Go to a Pentecostal church. Ask the elders to anoint your head with oil, lay on hands and pray in the Name of Jesus Christ. No need to tell them much, just say "an intestinal problem".
God can heal you.