Your trigger may nit be greasy food, but McD's is quite greasy. With your other food, take note of how its being prepared. Your trigger could be starchy foods (fries, potatoes). You may it figure out the trigger unless you try a food journal to fund out what the common issue is. Also, were you diagnosed wit IBS? If not, you might have a gluten intolerance. I know you may feel a doctor could pass you over, but you should try to talk to yours anyway. The kidney pain could be a symptom of tour issue or another issue entirely. It's best to get diagnosed so you can figure out how to stop or reduce your attacks.
I don't eat a lot of greasy foods. I may eat a macdonalds once or twice a week the rest of my meals r always meat veg n potatoes. I also get a pain near my kidneys, I know their something wrong n don't want doctors to pass me along as they do everyone else
What types of food are you eating for dinner? I was diagnosed with IBS when I was 13, and it took a few years for me to figure out that my trigger is anything greasy. When I have pizza, I have to mop up the grease on the top with paper towels to help. I guess the trigger can be different for other people, so maybe start a journal of what you're eating and which nights you feel sick and which nights you don't.