Hi, my 4 ur old son has a slight red rash (?) on skin near the corner of his mouth and the corner of the top lip by redness is swollen just in one spot. Favoring other side of mouth and rubbing his shirt to his mouth, like trying to wipe it. I ask if pain and he says not too much. Took away his nuk yesterday & gave it back tonight for bedtime. Do you know of any cause? Very scary. He s eating, drinking & sleeping fine and very healthy thank God.