Sales Dropped by 70% & Products not on first page

We have noticed that our sales have dropped of massively in the last 2-3 weeks and it is unusual even after considering seasonal downturns. We were easily selling 20-30 units a day each for our three main products, which reduced to 8-10 in late Feb and has become 2-3 in the last week. Suddenly our product is not on the first page of the results as well, i am not sure whats happening.

Due to decent sales last year we have stocked up quite a lot this year and this sudden downturn has become concerning. Does anyone have any insights or advice, it would be much appreacited.

Some other points

- We sell under generic brand, no brand registered

- No major negative reviews etc, all of our products are 4 star plus