Nipple shield side effects - reduced milk supply, difficulty in weaning the baby off the shield, poor weight gain, increased risk of mastitis and Nipple confusion.
So I would suggest -
1) you try and continue breastfeeding
2) if still unable to feed/baby not latching, then you can express milk and feed the baby via a steel paladai/cup-spoon, which is easier to clean.
Next Steps
Avoid bottle feeding strictly!