formula feeding! PLEASE HELP A SISTA OUT!

Kimberly • First time pregnancy and mom....all advise is welcomed 🤗
I breast feed during the day and formula feed at night. After feeding him the formula my baby cringes in pain. I feel so so bad but I feel like he is still hungry after breastfeeding which is why I formula feed. I was told feedings should be 3-4 hrs if formula fed and approximately 2 hrs if breastfeeding or whenever he wakes for a feeding (breastfeeding).
 
When i formula feed he can still wake up the next hour signaling he is hungry! Because I know he will be in pain I would breastfeed (at night) to avoid him crying. 
I'm a FTM in desperate need of help. Anyone else going through this or have any advice? BTW I am formula feeding about 3 oz to an almost 1 month old. Why is he in so much pain after formula feeding? What can I do?