Final answer:
The symptoms described are indicative of hand, foot, and mouth disease (HFMD), a viral infection that is most commonly seen in infants and young children. HFMD is highly contagious and resolves on its own within a week or two.
Step-by-step explanation:
The symptoms described, including poor feeding, vesicles in the mouth, and a rash on the buttocks, are indicative of a viral infection called hand, foot, and mouth disease (HFMD). HFMD is caused by the coxsackievirus or enterovirus, and it is most commonly seen in infants and young children. The disease is highly contagious and spreads through contact with nasal discharge, saliva, or feces of an infected person. While there is no specific treatment for HFMD, it usually resolves on its own within a week or two.