Tool to detect keyword "clouds" or "word patterns" from a source of data?

I have scraped 5,000 words of content.

What I'd like to do is run a tool to detect keyword usage or keyword patterns.

So, in other words, how many times a certain keyword is used (i.e. a "word cloud") or any other variations or patterns....does such a tool exist that you are aware of?

I am trying to detect sentiment with this experiment...thanks