Try to address the hides and temps those are the two most important things, if he was eating live rats keep offering that, do not offer alternative size prey it's usually not the solution but can create a bigger headache for you in the future.
If possible get a weight on him, a simple $10 kitchen scale will do, he seems of a good size and depending on the size since he is not an hatchling he might also have breeding on his mind, not to mention that older animals take a little longer to adjust.
He has some good size to him based on the little I see on the picture so that's not something I would be concerned about.
So address those then give it a week and offer food again in the enclosure and remove after 10/15 min if uneaten. Make sure the prey is sized adequately
Here is the chart. https://ball-pythons.net/forums/show...=1#post2493722
If that fail there are more trick such as downsizing the enclosure size but we are not there yet.
As for is a heat pad enough? well it depends every situation is different based on enclosure, average home temps etc. What you want to aim for is at least 76/78 cool and 88/90 hot with no greater fluctuation than that (temps fluctuation usually will create disturbance in their routine such as feeding). To achieve that some people only need a heat pad some may require 2 heat pad and 2 thermostat (which is the easiest way to achieve proper ambient temp on the cool side compare to keeping your room in the mid to high 70's)