this is a very serious situation. you should not be "evaluating" what antibiotics you should use that you have in the house for this. she needs to be seen by a health care provider. she may need stitches along with strong antibiotics because skin infections are very hard to treat and sometimes may even require iv antibiotics. you may want to call a "retail clinic" to see if they handle this local hospital to see if they have a walk in clinic etc. and if not go immediately to the emergency room.
my sister is a nursing mom & has an infected cut. she has amoxicillin and cephalexin. are either safe for her to take?