I constantly have worms

Over the past few years I’ve had worms several times a lot of the time they go away without medication however a month ago I took medicine to get them to go away and they are back!its super annoying having to ask my mum to buy it.She takes them to we clean everything my nails are always short and I wash them I just don’t understand how I have them !!

The water were I live isn’t contaminated and my mum never seems to get them