It would be difficult to say anything without having a look at the lesions and a proper clinical examination.
You could be having reaction to the drug. the chances that it is because
of missing the medication are minimal. Other than that, it could be due to some unrelated cause
You need to consult a dermatoloist or skin specialist for a confirmed diagnosis. Only then can
appropriate mediications be prescribed.
Till you get an appointment - keep the area clean, wear lose clothes.