HI, my son of 13 weeks nearly 3 months old has a lump between his back ear and jawline, it doesn t hurt and doesn t bothered him, been to the pediatrician , they did bloodtests and ultrasound and they re not really giving me an answer,cause the blood results were all good and the scan was lots of blood vessels; they think it might be a birthmark that comes up after 2months of age and goes slowly away again, but he had this lump 2 weeks after his first immunisation. He doesn t have any fever either.Is healthy as. The lump feels warm and goes up like a yoyo with hard and soft, big and small lump. They say that I have to wait another months (that in a couple more weeks time) Do I have to get worried? Also do u think it won t harm him if he flies on the airplane?