So sorry that you baby is suffering from HFMD at such a young age. I wouldn't give paracetamol if there's no fever.
It is important to keep your child from becoming dehydrated, so even though it may hurt to swallow, she'll need plenty of fluids, especially if she's running a fever. For your baby at 4 months , that means breast milk or formula. If it's hard for your baby to swallow, try giving her smaller amounts to drink more frequently than usual. I hope your baby get well soon.