Sales Dropped

[Tinle]

I am a new seller and I am trying to figure out what is going on. Long story short, we started with our first listing about a month ago. We did a Rebatekey campaign and wine and immediately started PPC campaigns. Sales increased steadily day after day and we started to average 8-10 units a day. We hit our record couple days ago with 22 units in one day. Then two days ago, on monday, sales plumeted. We sold 1 unit on monday, two units yesterday. What could be the cause of sharp decline?