my way would be to create a map of date and event.
Have a free content type called event_date_map
in afterstore of event item loop through dates in fieldx, create a date item if not already created for that date and then map event id with date id.
In searches use search join to link up mapped data
I have a plugin that does this if interested.
otherwise there is probably an easier way :)
also, does date work with fieldx?