I've done my BA in English which subject should I pursue next
Since you have already done your Bachelor's in English, you can neither pursue a degree in commerce, nor in science. You are only left with the field of humanities. In humanities, there are n number of sub-fields and specialties like Psychology, Hindi, Sociology, History, Geography, Economics, etc. What I would suggest, if I were in your position, is to take up Linguistics. It is a very vast field, a scientific study of language and a very up-and-coming field, students are in demand who have done Linguistics' course.