Girls, hello everyone! ❤️? Can it be that after six months of using on…

Girls, hello everyone! ❤️? Can it be that after six months of using one formula for a child, an allergy could occur? She constantly goes liquid with mucus and small blood clots (very few, but they are there). It's not red, dark. Before everything was fine, now something like this is happening. I talked to the pediatrician. She said to find the cause. For now, I am thinking about the formula.