Hi, My 2.5year Old Son Has Been Unwell For 3

Hi,
My 2.5year old son has been unwell for 3 days with high fever (he suffers with febrile seizures and has had another one on Monday - his 5th now - due to spike in temperature). We've followed all medical advice and his temperature returned to normal during the course of today. This evening his temperature has dropped, however, to 34.7 -35.1. I've wrapped him in an extra layer in bed to see if this helps bring his temperature up.

Is this the right thing to do?
Is it normal post fever for a child's temperature to drop?
I'm using a thermometer that goes under the armpit to measure his temperature.

I'm just seeking some reassurance as to whether to worry or not?

Thanks