If I am understanding your problem correctly then you could:
Make an Emergency Hex Key / Allen Wrench: This can be done by cutting the pointy writing tip off a pencil and cutting the edge down until it will fit. Pieces of wood of certain sizes can be used, as well. A plus is that the pencil can be reused afterwards.
Shave the sides of the pencil down to size. Keep the peelings parallel
to the faces. Make your shavings pretty thin. Test to see if it fits.
If it's tight, that's good.
Different types of screwdrivers are said to work, as well.
5 Ways to Improvise an Allen Wrench
A good example for smaller allen wrench nuts, you could likely use a
set of flat-tipped tweezers, or even the flat edge on a pair of finger
nail clippers. There are numbers of bathroom items that can be used in
such cases, and again it is about being able to turn or spin this
screw, nut or bolt to get it loose.
Sometimes you can use small types of flat headed screwdrivers as an
allen wrench by putting the end in the socket so that the 2 edges of
the screwdriver work as leverage in the hole to turn it. A wider
socket on the bolt or nut, use a wider flathead screwdriver. The
object here is to wedge the screwdriver into the hex of the bolt, to
create torque so it can be unscrewed.
You can also find great improvised allen wrench type devices in your
kitchen cupboard or in the silverware drawers. Flat tipped and strong
pairing knives could potentially work depending on the gauge and depth
of the hex screws hole. Remember you are simply trying to wedge your
tool into the hex so that you can spin or turn it