Baby poo question (a little tmi)

My daughter just turned a year old and we have been trying to find out what kinda milk she is able to have because when she was an infant she couldn’t have milk based formula so with that being said/done her poo isn’t normal and tonight when I changed her diaper and she had like this Mucousy stuff in her poo. And I got freaked out so of course I looked up online what it could be and it said it could be a bacterial or viral infection. Now I just freaked myself out even more. I’m going to be calling her doc right away in the morning but I was just wondering if anyone has had that happen with their child and what may have caused it? Thank you in advanced.