Can antibiotics make you itch in your genitals and cause a rash on legs, thighs, abdominal areas?

Monilia: ABs disturb normal bacterial flora of not only mouth but also gut and skin. In the locations you describe mostly likely causative agent is Monilia. Treatment is with topical anti fungal(Miconazole).Twice daily for 2 weeks. You should be tested for Diabetes.

Drug reaction: Some drug reactions are itchy rash, hives, facial swelling, vomiting, diarrhea, etc. These are typically considered allergic drug reactions and usually resolve by taking Benedryl and stopping the antibiotic. It is important to notify the treating physician of this reaction so that an allergy can be documented, and so that an alternative medicine can be prescribed to complete your treatment.