Welcome to HealthcareMagic forum.
Presuming the lesions were not there earlier, the rashes are most likely drug induced.
and other pencillin group of antibiotics can induce allergic reactions such as yours. And though steroid
therapy will be the treatment of choice, I encourage you to report to your doctor. He/she can note down your allergies and prescribe you an alternative antibiotic to treat the infection.
Hope this helps.