My baby is 10 months , currently teething.

since she was born we had an issue with GREY stool. I wanna add I know that could indicate liver or kidney issues but she has been checked for that and she’s fine She has had bloodwork and ultrasound on her stomach at 6 months. And drs stated she was fine that was just her “body”. I refuse to believe my baby is just having grey stool since she’s been born and nothing is wrong but her drs ignore it, She eats food, baby food, and recently tried a Reece cup as we are doing trunk or treating and we let her try a tiny piece. We switched her recently back to enfamil from similac due to her stool becoming more grey and firm on that formula. She always seems to do better on enfamil. We’ve chance it about 3 times per dr giving us the okay. (It was just for us trying to figure out the grey stool) but I don’t know seeing blood in her pamper made me feel sick. Grey poop now blood and this is normal for a 10 month old? Any idea what this could sound like? Her dad had a supposed milk intolerance as a baby. Nothing with me that I’m aware. What can I tell her dr to take me serious. What do I do or even say or request about this I want and need my baby to be fine and pain free.