Diaper rashes are very common and this happes because they grow in warm, moist places. Which makes the diaper the perfect place for the rash to develop. Factors that can make diaper rash are likely to include:

• when diapers are too tight

• sensitive skin

• irritated skin

• antibiotics

• introducing new foods

In some cases, a diaper rash can spread up to the child's legs and to their stomach. Fortunately, you can treat most mild cases at home. You can try these tips to help relieve your child's diaper rash.

Make sure to keep it clean and dry

Diapers needs to get changed often

Turn to disposable diapers

Look for the size of your baby's diaper

Apply soothing creams 

Source:https://www.healthline.com/health/home-remedies-diaper-rash