The exact cause of Psoriatic arthritis (PsA) is unknown.
The Arthritis Care website says in most case the arthritis develops after the appearance of psoriasis.
The website also says it can be difficult to diagnose because people have similar symptoms to other forms of arthritis.
Tracey Baxter has a friend, Anne Studer, who suffers from the same disease, but Anne says: “Whereas Devon has the arthritis worse, I have the psoriasis worse. It gets me down. It’s on my hands, elbows, legs, feet, just about everywhere. The only place I don’t get it is my face.
“It’s hereditary in my case and stress brings it out.”
Apart from medication for the arthritis and ointments and possibly light therapy for the psoriasis, there are things sufferers can do.
Arthritis Care recommends exercise to maintain muscle strength and mobility; rest for joints, and learning some relaxation techniques, which can help; and reducing the strain on joints by managing weight.
Contact the Arthritis Care helpline on 0808 800 4050. www.arthritiscare.org.uk