L.R.
Hi...I'm actually experiencing something similar with my 9 month old at daycare. From the beginning, we were doing the combo feeding, but he prefers breast feeding. Sometimes he did scream all day at daycare, but now he's transitioning a little better. It's been about a month.
My only suggestion for you is to pump milk and store it in the freezer. He may take that a little better than formula. You can also buy those bottles that allow babies to feed slower. I hope this helps.
Don't worry, they eventually do get used to other care givers. It's just a phase. Sometimes the initial adjustment is difficult.