My 3 month old sons stool changed 3 days ago slowly. Its kind of like gummy. like mucus dark green.?

I am worried he was pooping fine for 3 months and how all of a sudden he started pooping dark green and a liddo stretchy like gum and now its like a blob of green mucus and melted gum. . I havent changed his milk he takes similac sensitive since the beginning. . Is this normal or should i panic?