Tracking individual units for periodic actions

[Azrooh]

I'm trying to achieve this:
A unit is infected. During this period, he's infectious. After a certain amount of time, he starts taking damage. I can't figure out how to individually pick a unit after a certain amount of time's elapsed - I'm using USMWE and EGUI with Newgen, if that helps.

These are the triggers I'm using now, and they don't quite work. Would I be able to modify these to get what I'm asking?

• The Plague
  • Events
    • Time - Every 0.50 seconds of game time
  • Conditions
  • Actions
    • Unit Group - Pick every unit in PlagueGroup and do (Actions)
      • Loop - Actions
        • Region - Center PlagueIncubationRegion <gen> on (Position of (Picked unit))

• Plague Catching
  • Events
    • Unit - A unit enters PlagueIncubationRegion <gen>
  • Conditions
    • (PlagueIncubationRegion <gen> contains (Triggering unit)) Equal to True
    • ((Triggering unit) is A structure) Not equal to True
  • Actions
    • Unit Group - Add (Entering unit) to PlagueGroup
    • Start PlagueTimer[(Custom value of (Entering unit))] lasting 10.00 and One-shot and execute (Unit Group - Add (Entering unit) to PlagueDamageGroup) when it expires

• Plague Infected
  • Events
    • Time - Every 0.25 seconds of game time
  • Conditions
  • Actions
    • Unit Group - Pick every unit in PlagueDamageGroup and do (Actions)
      • Loop - Actions
        • Unit Group - Remove (Picked unit) from PlagueGroup
        • Unit - Set life of (Picked unit) to ((Life of (Picked unit)) - 4.00)
        • Unit Group - To PlagueGroup add units near (Position of (Picked unit)) in a range of 250.00 matching (((Triggering unit) is A structure) Not equal to True)

E: For the array, I was using a max (8192, I think) array variable and assigning it to the custom value of the unit.