I have more than one client how has lots of hundreds of likes and followers on her business page. So why are you losing followers and likes on Facebook?
The short answer is the algorithm is changing and your followers are also having the same issue. Lots of people are losing their accounts and being banned as well. Facebook is cleaning house. That will affect everyone.
It also is part of some Terms of service, so if you have ever invited someone to your page those invites might be rescinded.
There are all kinds of reasons right now, not all known to us why business page likes are disappearing into thin air. This is Facebook's right as a business to do what they want with their platform. Always keep this in mind when you are having issues right now. They are doing what they please with their audience, it is not your audience, it is THEIR audience. You have no ownership to the audience there on facebook.
This is why a forum like this is so important. Everything you post points back to you. While still gathering the ROI benefits back to your own site.