Well you clever lot, it looks like it’s going to be down to a deficiency of some sort. I spoke to the lovely chemist at Boots this afternoon and she said I’d need a blood test to confirm which deficiency is causing the problem. It could be any of the many already mentioned in your responses. Namely: magnesium, calcium, B-complex vitamins, especially biotin, and low calcium which contributes to dry, brittle nails. Also a lack of folic acid and vitamin C. So, I wasn’t sure I can actually bother the GP with this, it’s only nails but it’s so ugly. The chemist didn’t think they looked too bad, but I’d oiled them and painted with Dr Lewwins Renunail. When I showed her the photo I took pre treatment earlier today she said tell your GP I asked you to get a blood test. I have an annual one but I can’t read the results, I can see them but it means nothing to me. I do notice on the graphs though, each one seems to be taking a huge spiral downwards, but what do I know 🤷🏻♀️.