Didn't report hospital stay , need advice pls

Last year I was on Esa and PIP, in Dec I spent 3 nights in hospital. I didn't know I was supposed to report it to the DWP. I thought it was only for stays of 28 days or more. It didn't even cross my mind.

I'm now on UC(LCWRA) and ADP, I'm due to start a ADP review in on 19th August. I noticed on the review form (I saw online) it says if you have stayed in hospital you have to phone Scottish Social security (SSS) before filling in the review form, Ive been on ADP since April.

I don't know what to do, Ive been trying to contact local welfare rights but no one has replied. Should I contact PIP and ESA and tell I was in hospital or just phone SSS and inform them?

I'm really worried they're going to be really punitive and my life miserable. It was a genuine mistake.