Pls bring your baby to see a doctor. I recently experienced the same - baby had fever for 4 days. Despite taking paracetamol every 6 hours, the fever just kept coming back at 38.5 deg and above. On day 4 of fever, I brought baby to see a doc and they did blood test. Turned out that he is having bacteria infection of the lungs, hence breathing heavily - as pointed out by his doc. Was prescribed antibiotics, other meds and asked to use nebuliser to clear his lung infection. Aside from fever, my baby had bad cough, runny nose. But he still appeared active and hyper, despite the heavy breathing. Really wouldn’t have known something more serious was actually happening to him if we didn’t bring him to see a doctor. Please do not take fever lightly. Especially if it’s been ongoing for some time, better find out what’s wrong.
It could be baby's teething. However, if continuous fever for few weeks on and off with temperature of 38°C and above. I would bring to GP just for an ease of mind. My #2 had same thing too. We took blood test just to ensure she doesn't have dengue, influenza. However she did have low haemoglobin. That being said, it could be the cause of it. Which she will have another follow up on her 1 year old check up.
I was informed by PD and KKH before, that if temperature above 38C for more than 5 days, need to go see doctor. Teething may cause body temp to increase a little but usually not as high as 38C (which I believe is the threshold for fever) and not prolonged. Better take your LO to see doctor to check for possible infections / viruses.
I would bring my baby to a doctor