CW: Weird poop issues with my cat

For the past few weeks, my cat has been having weird poops. They're soft and malleable (I know this from using the scoop, I'm not some kinda weirdo lmao), and some of them are flat. Idk if they're coming out that way, or if they get flattened down when she buries them and then steps on top of the litter later. This started happening after I switched her food over to a vet-prescribed food to help with her constipation, but I'm not positive that it's related. Also, I recently started thinking that her gut feels bigger and firmer, but I can't tell if that's my paranoia or if it's legit. So I need to take her to the vet!

As a lot of you may know, vet procedures can be extremely expensive. She had constipation issues last year, and needed an x-ray, enema, and a laxative. It cost me over $400 for all of that. If she has an obstruction and needs surgery or an endoscope, that could cost me a few thousand dollars, and I'm super worried about that. I'm hoping it's just an issue with her food.

So I just signed up for some pet insurance through Progressive (whom my car insurance is through), but they have a clause about not covering treatment for any symptoms that occurred before the policy starts. There's got to be a way I can make this work, and need some input.

There's a 14 day waiting period, and after that, coverage starts. A few days after the waiting period ends, could I call a vet and tell them that this problem just started, and make that work?

Edit: I'm hoping I can cover any inconsistencies with the vet, like the timing of when I switched her food and when the symptoms started. I'm not great at lying, so I need help from more experienced connivers.