These little lumps you are feeling are most likely lymph nodes. These lymph nodes are the body’s defense mechanism against infection. They are normally the size of a pea, so even a normal sized lymph node is more easily felt in young children.
Often, lymph nodes will swell when there is an infection near the area. When babies develop certain types of diaper rash, they will sometimes develop enlarged nodes. Don’t worry, they will usually go down with time. Talk to your doctor, however, if you notice swollen glands all over your child’s body, the lymph nodes enlarge rapidly, or they become red and painful to the touch.