Migration ESA to UC, anxious about a new diagnosis

Hello, i am migrating from ESA to UC, in Support Group. I have anxiety anyway but Benefits impact my Mental Health severely. ESA and PIP reviews have seen me getting Crisis Team as i have gotten so ill mentally with them. I will use Citizensadvicehelpto claim with a Mental Health Navigator with me at Mind, as I read from this forum that they see the process all the way through.
I am terrified that a new diagnosis will trigger a UC 50. I may be overthinking this. My diagnosis include Chronic Fatigue and Mental Health, among others. I
In my list of diagnosis i used to write that I have generalised muscles and joints pain, due to a certain Health condition and medication. I didnt know until last year that my back pain and problems, which have been worse these last 2 years, are actually because i have Severe Lumbar Arthritis. My dr found out from an XRay dated 2016. My (different) dr at the time, had not requested this, i had the xray due to a fall whilst with a friend at the hospital, and i was not told about the severe arthritis. It explains years of problems. I
am so anxious about the Health Conditions part of the UC claim.
My friend suggested to write that part of the muscles and joints pain has now been 'confirmed as lower back arthritis '. I am so scared of it all. I dont want to get in trouble either later.

I have had 3 ESA reviews, 2013, 2015, 2018, all on paper with dr letter and evidence. It was due in November 2021, i was so anxious until Jan 2023 when i received a letter saying that there had been a change and i had been put in Support Group, I had not received an ESA50, it was all done without me knowing. I was so relieved and so thankful.
Thank you so very much for your help