I don't feel pinworms are big enough to see under the skin. I think you have other species of worms. But, whatever, they are probably roundworms which essentially respond to the same meds. The basic difference is if the meds are local (intestines) or systemic (whole body).
A pinworm medicine (pyrantel pomoate is a local--intestine only)) in Reese's pinworm medicine available at your pharmacy without a prescription and also available from your farm/feed store as a paste for horses. This med should clear most parasites in the colon--not just pinworms. It will not do anything for tapeworms, though.
You need to take every day for a week or two. All members of the family should take this medicine.
This is where I'd start. If your problems are not cleared up, let us know and we'll make other suggestions.
Suggestions for all the wiggling on your skin around the anus.
. wash your privates with Betadine Surgical Scrub available at the farm/feed store (an Iodine product)
. wash your privates with Hibiclens available at Walmart, most pharmacies and online (an antibacterial/antimicrobial skin cleaner). This product will offer you 6 hours of relief).
. do enemas to flush the lower intestines. Can use 1-2 tablespoons of white vinegar per 2 cups distilled water. Or can use 5-10 drops Miracle-Mineral-Supplement per 2 cups water. Just plain water will also help.