Dear Parent, Many thanks for your question on healthcaremagic.com. Your description does indeed sound like Pinworms. These little worms can often be seen on the surface of the stool. To be more sure, you may see other symptoms of pinworms. They often cause the anus to be sore and itchy, so you may find that your son seems uncomfortable and has some redness around his anus. If you check at night, you may even see some of the pinworms around his back passage. Pinworms are treated with a single dose of an anti-parasitic medication. You should be able to get this from your family doctor. Pinworms do not usually cause children to be systemically unwell, so the vomiting is unlikely to be related. He could have a co-incidental virus, or it could be related to his teething. Ensure he is well hydrated at all times with plenty of fluids. If the vomiting becomes regular or you are worried he is becoming dehydrated, he may need some more investigations. I hope this answer helps, if you require any further clarification or have further questions, do not hesitate to contact me. If it has helped you, please rate the answer!