I don't know how to check my website to see if it has been hacked. Could you share on the best way to do this?
The possibility I had in mind was that outbound links might have been added to your site via some kind of security breach. To check your site's external links, use Xenu's Link Sleuth, which is a free tool available download. (While we generally don't discuss specific tools in this forum, Xenu is a freeware industry standard.)
If your site is small, you might also check your pages on your server to see if any have been changed recently without your knowledge. If you've been making frequent content changes, though, those changes would mask other change dates.
From your comments about generally not doing well in Google, I'm thinking it's probably not a hacking problem, but more likely backlink and optimization issues. That said, it would be prudent to check, since you've disappeared for your page title.
To introduce another thought... is there a possibility that you also have overly frequent repetition of the same anchor text in your backlinks?
The changes happened within hours (approx. 2-4)
In the past, this would have been too soon to expect page changes to be reflected in serps. Since you've been having crawling issues too, I'd think it would be much too fast.
One suggestion about changes... when you make a page change, give it some time. It's bad practice to make a change, react too quickly, and change things again. You won't know what Google is seeing or considering... and in fact Google might respond negatively to too-frequent changes.