It is very common for babies to develop a mild fever after their 10-week immunizations, but this typically resolves within 24 to 48 hours. Since the fever is returning on the third night despite giving Crocin (paracetamol), it is important to have your baby evaluated by a pediatrician. While it could still be a lingering vaccine reaction, a fever lasting three days in a two-month-old warrants a professional checkup to rule out other infections. Please ensure your baby stays hydrated and dressed in light clothing. If you notice extreme sleepiness, poor feeding, or difficulty breathing, please seek medical care immediately.