If a python is being a fussy eater, and nothing has changed that might cause undue stress, then maybe it's just not hungry? My pythons have a more agressive feeding response fresh out of winter, but by mid summer when they have barely skipped a meal in months they can stop striking altogether and just pick up the meal and swallow. If they don't lose weight even though they're skipping meals, then it doesn't matter. Meanwhile, think about what might be causing a python stress? Has the enclosure moved, is there more foot traffic nearby, have you had a heat-wave or cold spell recently? (contrary to popular belief, hotter is not always better. I try very hard to give a broad temperature gradient. On hot days, I try to make sure the snake can access a cool spot. If your cool end is over 24 degrees, it might be too hot.) Just because it hasn't eaten, doesn't mean you should shove a rat in it's face every 3 days. That might just make things worse. Sometimes they just want to be left alone for a fortnight. Keep an eye out for any signs of ill-health, keep an eye out for weight loss, and don't panic.