It appears that your 14 mths old daughter is suffering from Urticaria
.The reason for such allergies could be food,viruses,bacteria,pollens,dustmites,preservatives perfume,lotions,soap etc.
Since the reasons are plenty you will actually have to think over as to what was new for her like even change in any baby products or environment etc.
At present you could apply calamine
lotion .If the rash
is itchy then you could also give her an antihistamine .If she doesn't seem to be alright then get her examined by her doctor.