If your 10-month-old is experiencing frequent liquid or mucousy bowel movements, along with worsening diaper rash, there are a few things you can do. Firstly, try to identify if the issue is related to her diet or possibly a virus. Time should help with the diarrhea, but if it persists for more than 5 days, consult a healthcare professional. As for the diaper rash, it's important to use a cream with a high concentration of zinc oxide to help reduce inflammation. Additionally, you can consider using a 0.5% hydrocortisone cream for a few days before applying the zinc oxide cream to further help with the rash. Make sure to apply these creams at each diaper change and after bath time.