Phalenopsis orchid leaves with black patches

[rbarata]

Originally Posted by sweta

...but now its spreading😭

In my experience those spots seems to be mechanical damage but there are more possible causes (such as insect bites that may leave a mark that darkens as time passes).
I wouldn't worry too much unless they spread to the point of affecting the whole leaf.
To avoid any possible infection caused by water deposits, put it in a warmer place, as ES sugested.