What do I do?!

I feel terrible. The WIC office told me that I would be able to mix dairy milk and formula for my little guy after he turned 11 months old. He is 11.5 months now so I have been mixing his formula. Tonight I read something that said that it can cause intestinal bleeding! I am freaking out over it now! He also just got his WIC yesterday and they aren't giving him any more formula. I don't have a lot of money to buy more formula. What do I do and will my baby be ok?! 😭😭