hello. I would recommend desitin cream (purple). please do change the diaper every 3 hours. Before changing to new diaper, use wet clean cotton balls to dap the pee area and also backside. I used tissues to dap dry the areas and apply the cream. hope it helps.
Another way is to see a doctor and he or she may recommend a mild steroid cream (e.g Desowen ) in order to treat the inflammation. Firstly, use Avent spring water to wash , apply steroid cream let it absorb and lastly, apply ceradan barrier cream