Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. My thoughts and suggestions are as below. Reese Pinworm medications may not cause peri-anal itching as you have also developed the diarrhea and nausea. This is suggestive of an intestinal infection. I would advise you the following in such a situation: Get the stool tests done to know the diagnosis and if there is an intestinal infection a course of an antibiotic active against intestinal infection, Metronidazole and probiotics will solve your problems. Clean the perianal area at least twice daily and keep it dry. You may apply liquid Povidone iodine locally. Medicines for worms to be taken if the stool test shows so. Use boiled and cooled water. No outside food. And clean the hands with soap and water every time you use bathroom or come from outside. Hope I have answered your query. Let me know if I can assist you further.