Lua [0.3.6] spell damage interval not working?

[Samaster]

Hello OTland, I have a problem with my script in that it says it will deal damage every 3 seconds (which is what I would like it to do), but deals damage like 3/4x a second. I've tried other values and it doesn't change anything so I know it's a problem with how its scripted. Can someone fix the problem for me please?

Here is the script:

local combat = createCombatObject()
local getPlayerLevel
setCombatParam(combat, COMBAT_PARAM_TYPE, COMBAT_PHYSICALDAMAGE)

function onGetFormulaValues(cid, level, skill)
   min = -level*1.5 -skill*5.5
   max = -level*1.6 -skill*5.6

   return min, max
end

setCombatCallback(combat, CALLBACK_PARAM_LEVELMAGICVALUE, "onGetFormulaValues")

function healMe(i, parameters)
if i > 0 and isPlayer(parameters.cid) then
  i = i-1
  addEvent(healMe, 3000, i, parameters)
    doCombat(parameters.cid, parameters.combat, parameters.var)
end
end

function onCastSpell(cid, var)
local i = 30
local parameters = {cid = cid, var = var, combat = combat}
healMe(i, parameters)
return doCombat(cid, combat, var)
end

It deals damage 30x but like i said, 3/4 times a second rather than once a second.

Thanks,
Sam