yesterday I have trimmed nails of my feet. so a small wound happened to my thumb. I hv cleaned it. but this morning when I took out shoe for doing wazu for jummah namaz, I saw a yellow coloured dry substance on the nail. so I don't know if it is blood or some curry which might have felt on the thumb while doing breakfast. what to do? bcz if it was blood then my shoe n socks might became najis.