To track changes in Discovery you are basically stuck using two query functions historySubset or displayHistory, neither of which are very output friendly.
To see all migrations for a particular host for say the past 30 days something like -
search Host where name = 'xxxxxx'
historySubset(#, currentTime() - (30 * 24 * 3600 * 10000000), currentTime(),,["ContainedHost:HostContainment:HostContainer:VirtualMachine"])
should do it.
Alternatively if you have the vCenter Event Source enabled then you can look for the required hostname in the vcenter event messages:
search ExternalEvent where __source = 'vCenter' and message has substring 'xxxxx'
SHOW event_time, message, type
obviously the time this data is kept for will depend on your Event Removal settings.
Thanks, that helps