You must provide correct temps.
You will absolutely need a temp gun. You can buy this at home depot. Without a temp gun you will NOT know the surface temps of the enclosure.
When you buy the temp gun, point it at the basking spot and if it isn't up to 130 then you need some adjusting to do.
Do NOT go the route of just one big bulb. It will reduce the ambient temps in the cage and you will have only ONE hot spot and the rest of the cage will be too cool for him to digest his food properly and he will not eat because of it.
Of course this all depends on what kind of enclosure you have for him. Is it a fish tank with a screen top? If so, DITCH IT. Build something for him before it's too late. Fish tanks kill monitors, simply PUT.
Build a 6x4x4 if you can and if you can't then have somebody do it for you. If you don't have the means to build a big cage then you should not have the monitor. Gotta man up and do things properly if you want a healthy lizard that will live past 2 years.
You should be aiming for humidity at a constant 50-60%. No higher, no lower.
The air temps of the cage should be between 85 and 77 degrees. Not much higher, definitely not any lower.
These monitors need to be able to get hot QUICK in their natural habitats. Staying out basking for too long = chances of being eaten by an eagle or other predator increase.
Of course they don't have to worry about predators in captivity but they still like to be able to get really hot really fast to START their day. Then when the air temps increase after morning they usually like to chill out somewhere away from the basking spot and rest only to wake up later to get really hot really fast again.
He won't eat if he is stressed out from being handled.
He won't eat if he is stressed out from a crappy cage.
That is why it's good to get them in a nice big cage as a baby AS SOON AS POSSIBLE so that they can get into a schedule with correct husbandry.
-WRC