I've seen them get more vocal, and demand a little more attention during a heat, but never shaky.
I would run her by the vet, to make sure she doesn't have something else going on.
Not all those who wander are lost.
Life is just a leap of faith.
Spread your arms and hold your breath and always trust your cape.
Two things define you. Your patience when you have nothing, and your attitude when you have everything.