Flat head is very commonly seen and it resolves easily .
1. Re-position your baby’s head (from left to right, right to left) when your baby is sleeping on his back with the rounded side of the head touching the mattress and the flattened side facing up.
2. " Baby head shaping pillow " are avaialble in amazon also.. they are specially designed for this
Next Steps
Regarding vaccinatn :
it's late by a few days.. nothing will happen.
Now vaccinate him the missed dose
Health Tips
observe ur baby sleeping position