Walking helps??? HOW??

I keep seeing people talking about walking walking walking. I have a L5-S1 disc hernation, started at the beginning of January. Chiro, then PT for 6 weeks.

I have a two year old so laying down all day isnt even an option. Im on my feet and walking a lot during the day and its hell. Ive been in constant all day pain since January. The past month or so has been the worst. I cant even walk upright, and i cant go more than a few feet without my back feeling like its collapsing, and my leg feeling like its going to give out. now im getting a very cold sensation in my back when i stand too long.

The only thing ive noticed help the pain feel a little better is... when i basically lay down and do nothing all day, which doesnt happen very often.

I just sont undersant how people to say to keep walking when it truly feels like that makes thing ao much worse for me. Which i love walking and was proud of my 10,000-12,000 step average before this pain started.

I dont understand what im doing wrong, i just want to feel normal again