Firstly, I think you have been waiting too long to see a skin doctor. You should seek an appointment and do so, as this repetitive use of creams and antibiotics is not taking you anywhere. Scabbing is seen with bacterial infections, as you correctly surmised, but I am not too sure this is staph. May be, she needs a course of oral antibiotics
. Consult her doctor for the same and to take prescriptions. Basically, in 8 out of 10 cases, skin specialists can diagnose the condition without taking any tests.