My son, who is almost 2 years old, is complaining about a "boo-boo". I noticed that his toenail is a bit under the skin of his big toe.

It is possible that your child has an ingrown toenail, which occurs when the nail grows into the skin. This can cause pain, redness, and swelling. You can try placing dental floss under the nail where it is digging into the skin, or soaking the foot in warm, soapy water for 20 minutes, three times a day for two weeks. However, if the situation does not improve or worsens, if there is significant redness and swelling, if there is pus draining, or if your child has a fever, it is recommended to consult a doctor or a podiatrist.