OMG... Poor child. It's most likely Ascaris (larger roundworm). It's def not pinworms. You should treat your child ASAP. The most likely medicine which you can use is called 'mebendazole'. However don't administer it without consulting a doctor. Since this drug has not been extensively studied in children under two years. 11 months is radically different reg immune system. Ascaris can stunt the growth and general development of a child. So yeah pretty serious. But plz don't panic... Hard to do esp when it comes to your child.