Coincidence or causal? Flu and Psoriatic Arthritis

Hi, I was diagnosed with psoriatic arthritis last year after having been investigated for nearly two years. I am a 44 year-old female. My father had psoriatic arthritis quite badly. I have other autoimmune conditions - coeliac disease (started in my teens but not diagnosed until 29 yo) and hypothyroidism (Hashimoto's thyroiditis). My PSA presents as extremely painful kneecaps, very swollen knees, very painful right ankle around the inner ankle bone down to the heel bone and is permanently swollen there, very painful area symmetrically around the back tips of my shoulder blades, pain around the spine in between my shoulder blades, extremely stiff neck, sore wrists, painful chest bone area and where the collarbone meets the shoulders (both sides), and more recently, my left jaw bone where it meets the ear area. Skin symptoms include dry, itchy skin generally, very itchy inner ears, itchy scalp, occasional small very dry patches with bumps, occasional isolated (only one, not multiple) discoid shaped rough raised patches (on my spine, lower legs). Treatment - I am about to start on methotrexate, because the NHS in Scotland requires PSA patients to try that first - I am only allowed to try biologics if the methotrexate doesn't work. For the past two years I've had to take ibuprofen and paracetamol to help with the above pain, but as you all probably know, they don't do much to reduce the pain. I have a prescription for naproxen, which I only take very occasionally, to avoid damaging my stomach, and mostly before bedtime to ensure a good night's sleep. Very rarely, I take it in the morning too. So... I noticed a very strange phenomenon earlier this month when I caught flu. The flu was a bit weird compared to previous times - it made me feel dizzy, which I've never suffered from below - the flu could have been one of the new strains that arose during 2024 winter. On about the second day of the flu, I noticed that when I got up in the morning, I didn't feel the usual severe stiffness and pain. On around day three of the flu, I noticed that the swelling around my knees had diminished significantly. Then, on around day four, the swelling had gone - completely. The pain and stiffness had gone - everywhere. I felt so much better physically except for, of course, having a flu. The flu gave me muscle aches, dizziness, tiredness (but not fatigue), cognitive fog, sensitivity to light, and then sinusitis and a mild chesty cough. However, despite those flu symptoms, I really did feel much better whole body thanks to the disappearance of my psoriatic arthritis! And then, as I felt the flu diminish, the arthritis came back slowly. I am now in the midst of a bad flare-up (two weeks since the flu went away). Has anyone here noticed their arthritis symptoms disappearing when they have a flu? I am probably just grasping at straws, but it seemed uncanny.