Could my sister's frequent colds be related to blood in stool?

Hi. It’s regarding my younger sister she’s 4. After Eid, she stopped eating and lost weight a bit. But she’s been eating well again for the last 2 weeks so her appetite is back to normal. She had an ear infection and flu right before she lost her appetite but her appetite loss happened after finishing the antibiotics. However, over the past months she always says ‘my leg hurts’ and she says it’s her ankle. It doesn’t make her cry or anything and it doesn’t stop her playing like a wild animal ???? but today she has blood in her poo and on tissue when wiping it was bright red blood it’s happened before when she was constipated she didn’t drink much water yesterday and my other sister also got the norovirus so it could be that- her poo was watery. She also catches colds frequently