Spent the morning with a Mr, being x-rayed and foot massaged. Nice to get an expert opinion on the sprain as well as what I actually went for.
As this is a cycling forum I can use our terminology: I'm getting my hot-foot sorted. After years of 'stiffer soles' 'wide footbeds' Road vs SPD and cleat positioning, I went to see an expert.
Diagnosis - mechanical, probably not a neuroma, bursitis and metatarsalgia. First stop, a pro about orthotics, back to the mister in 4 weeks for steroid injection and repeat ultrasound and if none of that works, surgery.
I liked him. He listened, and looked, and had a good foot fondle.