Colic and Flatulence are common after formula milk.. you can work on increasing your breast milk output using some galactogogues and frequent milk expression and or breast pumping.. once it's calibrated you can enough milk for your baby.. A mother in first 6 months of lactation secretes around 700 to 800 ml breast milk that can easily mitigate hunger of even triplets....
Next Steps
Try manual hand breast milk expression using the MARMET technique . you can add breast pumping to you session. at least 7 to 8 milk expression per day.
Health Tips
Changing formula won't solve the issue...Medical literature says some Lactase enzymes can help in solving Flatulence and colic..