Ay mommy, sobrang understandable ang worries mo, pero based sa description mo, mukhang hindi HFMD ang signs niya, HFMD usually may characteristic rashes talaga sa palad at talampakan, hindi lang sa face and body like what you're seeing. The fever on and off could be from the UTI itself or from the antibiotics adjusting sa system niya, kaya I'd really push to follow up with your pedia about this, mention the rashes and the fever pattern specifically, para ma-rule out niya properly and ma-assess if the antibiotic is working or if baby needs something else. One of my mum friends had similar worry din, turned out it was just the infection causing the fever, so don't panic muna, mommy! Keep monitoring her temperature and those mouth sores, at message agad the pedia if fever gets higher or the rashes spread fast, okay?