Yesterday was bad, today is insanely bad

I have a campagne that has been running strong for 3 weeks, no signs of fatigue or anything.

Around 10 conversions a day, good CPA.

All of sudden on the 24th, 0 conversions.
The 25th, a few conversions, CPA tripled, very low quality traffic.
26th, 27th, slightly better, but still bad.
28th, half my budget already spent, 0 conversion.

you need waiting for result few days do not take decession quickly.and find keyword or campaign which wastage your budget is it relevant or not.