It could be pinworms, they are very common, especially in kids, and they have nothing to do with hygiene. They are highly infective, so get to a doc, make tests (stool test and scotch tape test), then get treatment for you and your whole family. Repeat treatment for at two more times, waiting about 21 days between treatments.
Good luck.
out of county doc needs a full panel sound like worms tape or others also might be or have other parasites a full panel should pick these up
other country's have horrible hygiene and cooking habits
it may take a while and some nasty pills but ride it out and follow all directions and never stop meds early