MY Mother Is Allergic To Keflex-rash Head To Foot. She

MY mother is allergic to keflex-rash head to foot. She is in hospital now for "cellulitis". They gave her Iv rocephin despite my reminder that she is allergic to cephlosporins. The 'hospitalist' told me "thats what we have benadryl for and its a 3rd generation". He temp shot up again 104.3 rectal and had projectile emisis. Am I wrong that when we have so many other antibiotics available-give her something else?
We went throuoght his in January and she took cleocin without difficulty.