My 11month old hasn't been himself since Thursday afternoon.

You are most welcome.

Kindly let me know about the following so I can help you best.

1. Is the child active and interacting as usual and eating and drinking as usual?
2. how many full diapers is he having in 24 hours?
3. Any shortness of breath, noisy breathing, etc?
4. What is his respiration rate? (count his breathing in one minute)

I will be writing an answer and will respond soon. Please allow me 10-15 minutes.

The symptoms the child is having are very likely due to a viral infection. These are generally self limited and get better in the next few days to one week. At the moment, I would continue to give the child nurofen and panadol  to help with the fever and possible pain he may be having. Follow the dose instructions on the package for the child's age or weight so that you make sure you give the optimal dose. If you alternate these two medications, keep note of which you give and at what time so to make sure you do not risk overdosing the child.

Give plenty to drink so the child is kept well hydrated and keep an eye on the child.

In the less likely case that the fever lasts more than 72 hours, it is not responding to the medications, the child is sleeping more then usual or is less responsive and not interacting as usual, if there is any shortness of breath, noisy breathing, vomiting, the child looks unwell, etc, a check as soon as possible would be needed.

Please let me know if you will have any additional questions related to this.