Fussy baby...

I breastfeed and supplement with formula about 4-6 ounces a day. Something is causing my son to arch his back, have gas and refuse feedings. I'm wondering if I should take more drastic measures and quit dairy. Any of you have specific diets (if breastfeeding) or brands of formula that worked well for a fussy baby? This has been issue for me since day one but he goes through phases where it's better so I often forget about it 🤷‍♀️