HELP! Is a small bit of mucus in baby stool bad?

Not sure but it's prob just the new solid foods and maybe it could be sickness leaving body. I wouldn't be too worried if that's all.

Oh I've always heard that bananas cause constipation in some peeps

Most infants, even those fed formula, have frequent, watery stools until they are six to eight weeks old. After that, the stools become firmer and less frequent. In fact, infants who are only fed breast milk beyond the first two months of life may have a stool only every three to five days. As long as the stool is soft, this is normal. Babies' stools are firmer once they start on solid food.

To answer the last post, she is 4 1/2 months old. She is formula fed. She has all ready started solids.. been on cereal for over a month.

An allergic reaction will NOT cause a fever.

Monitor her fever. Monitor her diapers and watch for vomiting.

If the yellow colored poop had the worst smell you've ever smelled with it, it might be rotavirus. MIGHT.

Something to be worried about? No. Just keep a eye on her and if she does start vomiting, call the pediatrician and see what he recommends for your daughter.

wanted to add to what ticcedblue said, if the mucusy stuff/runny poops last more than a few days, call doc as they can dehydrate very fast. look for sunken eyes, sunken soft spot, dry lips and lethargy...any of which warrant a doc call.