It is important to note that scalp
infections often give rise to lymph node swellings in the neck region which is the cause of the "marble sized lump" which you mentioned. Bactrum is used to treat scalp infections but if the infection has lasted for a long time, you need to show the Pediatrician
whether the infection has progressed or is under control. If the condition is serious a course of oral antibiotics
will help. At the same time, do ask her how exactly she got the bruise
. Whether she got hurt with some object.