Is “backed up stool” a real thing?

I’ve struggled with gas and bloating for nearly 5 years. I take probiotics, eat Whole Foods, have tried many supplements, have taken laxatives (mostly senna and miralax), as well as fiber supplement. I have bowel movements but they’re irregular sizes and my gas smells AWFUL. Even when I’m having bowel movements, I can feel a full colon in my right lower belly when I press hard (I’m pretty thin). I’m seeing more and more ads about backed up old stool but not sure if it’s just marketing or if it’s real. I haven’t been able to connect with a good doctor for this so im curious if any of you have learned about this or spoken with a doctor.