I had a colonoscopy 5 years ago for this exact same thing, so I truly shouldn't be freaking out right now, but this is how my mind seems to be working now.

I recently was on vacation with my family for 5 days and for the last 3 of those days I wasn't able to have a bowel movement. That's pretty typical of me, even when using miralax. I just don't poop on vacation for whatever reason. Anyway, I took miralax 3 nights and when we came home, I finally had a good full. Work movement...and then a few more. This morning I did the same, more clearing out obviously. But in the midst of all of this I have been having this lower left side pain, only when I'm walking, or when I sit down. It's calm if I'm completely still, but if I move at all in a way that makes my colon move, I have a sharp pain. It wasn't any better after a bowel movement, but it also didn't begin until I started clearing out all the stool that I wasn't able to get rid of during my short vacation.
Again, I had this same thing happen about 5 years ago, they suspected diverticulitis and treated me for it, but when I went in for a colonoscopy, they didn't find any pockets or reason for the pain, so they just said it's IBS. I have had these feelings off and on over the years, but they're usually much milder. Today it's pretty painful and I'm freaking out.
I have no insurance, so the dr visit for reassurance is not really the best idea.

The only thing I'm concerned about is it being diverticulitis. That can get serious if left untreated. But what I am hoping to understand is if diverticulitis would get progressively worse to a point where I would KNOW I need to be seen, or is it possible that diverticulitis could hang on mildly like this and still cause bowel perforation? I'm worried about not being seen, but worried about thiunsanda of dollars in medical bills just because I'm freaking out.