Hi @maudie01, welcome to Connect. I know it can be scary when a child gets high fevers and especially unnerving if the are reoccurring. Hopefully other members will be able to share some suggestions with you from their experience. You might find the following Mayo Clinic Q & A helpful.

Mayo Clinic Q and A: Child with recurrent fever may have periodic fever syndrome
-- https://newsnetwork.mayoclinic.org/discussion/mayo-clinic-q-and-a-child-with-recurrent-fever-may-have-periodic-fever-syndrome/

I noticed you also started another new discussion with the same topic here: https://connect.mayoclinic.org/discussion/fever-1/. I'm tagging our moderator @ethanmcconkey to see if we should combine your two discussions with the following similar discussion:

Groups > About Kids & Teens > Toddler has had fevers for over 3 weeks. No one knows why.
-- https://connect.mayoclinic.org/discussion/toddler-has-had-fevers-for-over-3-weeks-no-one-knows-why/

May I ask how old your grandchild is? Have the doctors given any diagnosis or tests for the child?