Swollen toe

Jordan is a 15 year old boy who presents with a swollen toe to accident and emergency. 

He is a keen footballer but cannot recall any injury. Otherwise he is well with no systemic features to suggest red flags in the history and the examination is otherwise reported as normal from the emergency department assessment. He has a swollen toe ('sausage like').

Investigations - radiograph shows no fracture. Ultrasound shows soft tissue swelling and effusion in the interphalangeal joint and metatarsal joint.  Full [complete] blood count, acute phase reactants normal. Autoantibodies are normal. 

He is referred to orthopaedics who perform aspiration of the toe joint under anaesthetic. Cultures are negative but he has a six week course of antibiotics. 

At review, he is no better and now has pain in his fingers. He is referred to paediatric rheumatology.