Applying for PIP for my hip pain and how it affects me daily

Hi,

I am applying for PIP again (as I lost the appeal for Mandatory Reconsideration Notice, was awarded 0 points again) for my hip pain. I decided to apply for a self employed delivery job (out of desperation as I need money) few months ago, been working since then but it's a huge struggle. I can only walk a few minutes till I have to rest in between and if a customer has stairs, I have to ask him/her to come down or I leave their items on the ground floor. It's just food deliveries, usually weighing no more than 2 or 3KG.

And to collect the item, I can ask the restaurant to drop off their parcel to me. I use my car for delivery. And it takes a few minutes to drive to a customer, most of them are usually located within 1 mile.

I'm wondering if DWP would deny me PIP because I'm doing a job that's totally not suitable with my hip condition. Since it's self employed, I often take many days of rest in between because of the sheer lower back pain I get along with hip and frequently get pins & needles.

I'm thinking if I have to mention about my job or not. And if they ask me what job I do, am I able to legally say "I don't wish to answer" or do I have to tell them?

Kindly please let me know. Thanks.