Thumb nail became curved.kinda like clubbing in only one nail except that schamroth window is there. my nail is just bulging like an upside down spoon?

Interesting finding: This is interesting that only your thumb is exhibiting "clubbing". This is likely a good thing, since it indicates that the problem, if there is a problem at all, is localized to the thumb/thumbnail/nail bed. There are some things that grow in and around the nail that might cause it to bow outward (clubbing). These include a glomus tumor, myxoid cyst, or an osteoma. Let a doctor look at it.