Keflex and penicillin allergy

Has anybody with a penicillin allergy ever took keflex? I'm allergic and they prescribed me this another doctor at the er prescribed me microbid but my family doctor said keflex is better for breastfeeding...I was warned that with a penicillin allergy I could have a small allergic reaction..I had my baby 2 weeks ago and was diagnosed with postpartum hypertension and had to start bp meds..now a uti and possibly having a reaction is scaring me ...I have severe anxiety and want this uti gone but I'm scared to have a reaction to keflex...