First know that, as long as your BP does not loose too much weight he will be fine, second try to proceed by elimination to find out if there is anything that can be done so your BP resume feeding.

Check your temperature and make sure they are 80-84 on the cool side, 90-94 on the warm side, of course this mean you need to have an accurate reading provided by a digital thermometer/hygrometer.

Check your humidity and make sure it is between 50%-60%

Make sure the enclosure is in a low traffic area.

Make sure your enclosure is the appropriated size, an enclosure that is too big can be overwhelming, and can cause stress overtime.

Make sure your hides are tight enough so your BP can snug in, all sides must be touching your BP's body.

If you handle your BP often, try to limit handling (Too much handling can cause stress)

Ball Pythons will also fast to catch up if the prey they have eaten in the past are too big or if you feed them too often.