Diaper rash ..... Please help !!!!

So my daughter has had this diaper rash for about 4 days now it looks so red and has bumps it doesn't seem to get any better i've used diaper rash cream, vaseline, a&d and now i'm about to use corn starch(but someone said it's not reccomended for baby girls) and I also heard taking your baby a bath in baking soda helps. I took my baby a bath today btw and I changed her diaper brand as well as baby wipes but nothing seems to be helping :( if it doesn't get better, i'm going to take her to the doctor tommorow or by this week. Does anyone know anything that can help ?