Facebook Page Post Reach Dropped!!

Hello guys,
I am a Facebook Influencer from Nigeria.
I have a 4 years old Facebook page with over 2.9M Likes and all we do is post babies and maternity Pictures. Everything was good until last week when I noticed my post reach dropped. I used to record 150K to 200K (5K - 10K likes in 24 hours) post reach on pictures and 7M - 15M (pictures & videos) whenever I go viral but right now, I get about 5K post reach and 50 likes on a posts and the engaging ones gets about 200 - 400 likes. I thought maybe my page was ghosted so I boosted some posts and surprisingly I got 3K likes in 24hrs (I spent about 4 euros). I can't continue to spend on Facebook ads and I barely make money on my page because I don't know how affiliated marketing works. My page post reach is now so bad that is depressing, people don't engage anymore and all my fans are orgnaic. What maybe wrong?

Just share links to make money like instant article or adsense , and keep boosting because if you stop boosting ,then after few days facebook will lower your reach

Last month, My page was doing fine without boosting. Facebook just wanted to ruin everything for me.