I now know what caused my pain. It's still terrible sore and swollen.
OH kicked me in his sleep. He did it twice last night. We sleep back to back and his foot shots across the bed like a whiplash. He caught me on my bad foot and my other one last night.
That's how come it happened so quickly last week. I must have been so deeply asleep then I didn't realise. That's how I could identify the exact spot where he caught me.
Tonight there is going to be a pillow down the bottom of the bed.