Does the rash feel slightly rough to the touch? Is she scratching it or showing other signs of discomfort with it?
If so, make some oat milk by placing a dessert spoonful of organic porage/porridge oats into a muslin square if you have one or if not an old popsock or the foot part of an old pair of tights. Tie a knot in the fabric leaving the oats a bit of space to expand.
Place the oats in the fabric in a bowl and add very warm water. Leave to soak for a few minutes til the oats soften, then squeeze the fabric a lot to extract the liquid from the oats, it's called oat milk and is thick and opaque.
You can patch-test an area of the rash by dabbing the oat milk on it and not rinsing it off, give it an hour and see if it's less red. If baby's showed no sign of irritation, tip the rest of the oat milk into the baby's bathwater, it feels lovely and silky, it may be slippery so take extra care. Again don't rinse off, pat dry and see if there's any difference in the rash in about an hour or two.
Oat milk has long been known as a home remedy for eczema, I have 21 years and counting experience of treating it and nothing takes the fire away like it can. I'm no fan of treating skin with steroids, it's up to you what you are comfortable using on your baby.
For dry skin in general, try using organic virgin coconut oil www.amazon.co.uk/Org-Raw-Virgin-Coconut-Oil/dp/B004JBVHVC/ref=sr_1_2?ie=UTF8&qid=1403379928&sr=8-2&keywords=coconut+oil+biona as a moisturiser, but not obviously anywhere the sun could catch it as the baby's skin may burn with any type of oil on it. 'Baby Oil' is petrochemical based so if you prefer a natural alternative, coconut is a good place to start. Incidentally, t's also been beneficial for a friend's DH's Psoriasis.
Please do check your washing powder and fabric softener, they can cause havoc on sensitive skin, I use the Eco Egg laundry egg, the fragrance free type. www.ecoegg.com/product/laundry-egg/
"Voted the top Gold Award for best Baby Skincare Product by Prima Baby & Pregnancy Magazine, our award-winning Fragrance Free Laundry Egg is perfect for a baby’s delicate skin. It’s supported by the National Eczema Society and is also great for adults with sensitive skin conditions."
Are you starting weaning? if so make a note of foods you introduce and any rash severity, they may be linked. Cows milk is often a culprit as are carrots but everyone has their own triggers for allergy or intolerance.
Do go to your GP as often as you need, especially with such a young baby, internet advice no matter how well-meaning can be unsuitable. It's important to have a correct diagnosis before you decide how to treat the condition and if you are happy with the steroids etc. then use them 