If you have the slightest idea of how cheat engine works I could help you through it.
Sadly enough I do not own this game on Steam and thus can't scan it myself.
In the beginning Naija's health is 5, with every upgrade you get one health with that.
A fully 'upgraded' Naija has thus 10 health.
Now, the health is a float, so you should scan only for that (there is a drop down box, default is "4 bytes").
You start scanning with the amount of health you have (10, or 5, or 6,7,8,9, depending how many health eggs you got), then get hurt, pause the game and search for a decreased or increased value you could pinpoint the health and freeze it. If after one try you still have too many values, get hurt or heal again and search increased or decreased again!
I hope this helped, if you want I'll make a walkthrough with pictures, but please try first.
I couldn't find anything against reviving threads, so forgive me if I've broken a rule somewhere.
This is for all the other chronic cheaters out there, hope this is helpful somehow.
I've done some light study with the HP code, and have found some interesting things. A key note here is that I used the steam version and Cheat Engine version 5.6.1 in this.
There is an address that stores your current health and remains constant between executions of the game. For me, it is 0017DE58. I use the value stored here to find the address that actually has an effect on health.
The real HP address almost always changes when you move to a new map, especially if the value is frozen. There is a chance that the address won't change, if the value is not frozen, in areas that are similar (map groups?). An example would be (I dunno if it's a spoiler or not)
Mithalas Palace -> Mithalas Cathedral. Something to look for to see if the address has changed or not is to watch the unfrozen value when moving from map to map. If the value changes to a long line of numbers, negative number, or a number higher than your max health, then it's changed. If it changes from your current HP to the HP from the beginning of the game back to your current HP, for example 6 -> 5 -> 6 (I had 6 HP when i actually did the test), then the address has not changed. I'll test this further once i have more HP.
One last thing to keep in mind is to not try to find the pointer address for the actual HP address (the really real HP address that tells the game what the address we've been using to modify health is and what it will be when the game says to change it). The reason for this is that every time I've attempted it, my game crashed whenever I took any damage. I haven't found any file damage (save or game), but it's still something to watch out for.