BCG vaccine

Hi mommies! FTM here, pahelp nman po, bakit kaya my nana at namumula mula ung bakuna ni baby ko sa braso? 1month 6days palang sya at yung bakuna nya is nung pang 10days nya plng pinanganak.. Nakakaworry dn kc, pero sabi nla normal lang daw toh? Yung pic1 is kuha nung last 3days..tas now lang ung 2nd pic