Rash on back

[Embmum]

Just noticed this rash on 7mo daughters back when giving her a bath tonight. She’s not been unwell recently - was her normal self all day. Anybody seen anything similar before and know what it could be?

Looks like Hives-does she have any allergies?

She’s currently on Pepti milk as could potentially have cows milk sensitivity - still uncertain though. We’ve kept all milk out her diet except this morning I accidentally gave her a rice cake which said unsuitable for those with milk sensitivities - despite not having milk in the ingredients. Do you think it’s that? Man I feel awful :(