Problem with Facebook ads - over 70% drop of clicks, views, impressions and sales. Help!

Greetings, dear Warrior Forum members!
I've been reading information from this forum since many years, but never had to sign up... Until now.
I'm in need of your valuable advices and tips, because I have a problem that is destroying 2/3 of my business...

This is the problem:

I have created an ad more than 2 weeks ago. It is targeting Bulgarian women at the age between 20 and 35 years. With a daily budget of around 17 USD (30 BGN). Actually I'm usually setting up a bugdet for the whole period, so let's say 500 USD for 30 days. The campaign's objective was website clicks to my online shop.
At the start for a couple of days - I was getting over 1500 clicks to my website daily... After that I had to make a pause for a couple of hours due lack of funds in my card, I quickly deposited again and restarted the ad...
During the next couple of days - it started getting only between 150 and 200 clicks daily... And the sales were also 6-7 times (X) worse...
At first I thought that there is a problem with my website/wordpress platform, but - no, when I checked the Facebook page and ads reach - it seems that the ad itself is getting at least 8 times less impressions with the same buget...
What is the problem and how can I fix it, please? Any help would be appreciated!
Because I'm getting less visitse to my site and therefore - less sales and less profit... I'm barely covering my daily budget (some days I even don't) and at the start - it was going perfect with 1500 clicks daily, with between 0.01 and 0.02 USD price per click and now it's at arround 0.12 - 0.13 and this is too expensive for the Bulgarian market compared to other ads...
Btw - I'm running other ad to another website and there is no such sudden drop in impressions and clicks. Facebook is serving this ad to less people...

Pls...