Fever after immunisation

Hi, my lo (7 mths plus going 8) just went for her immunisation in the morning around 9.30am, reached home at about 10am & let her nap cos she was damn tired, when she woke up at about 11.45 (usually she can sleep more than 2 hrs), we fed porridge but she didn't want so we gave milk & she drink, wait awhile & gave paracetamol as her fever came at around 12pm. we broke the 6 hr rule & gave her paracetamol again after 4 hrs (1.30pm & 5.30pm) as she didn't gave the full dose (dr say 3ml, we gave 2ml) but her fever is still hoovering at around 38.1-38.4 I know some kids will have fever but at what point do I have to bring her to the doctors? she can't sleep, can't really do anything cos she feels damn lethargic. do I continue waiting? thanks