Campaign died mid way... why?

I had one campaign, one adset, one ad, very simple setup.

It was performing well for 2 months. If I tired to vary a creative, new style of ad, new landing page... nothing worked all those would take back seat and die. It was just is those killer ad in one adset that carried campaign for 2 months.

Then I did something stupid in retrospect, I don't have much experience. I figured out the days of the week when there would be a spike in sales... so I started to reduce budget on off days and pump that budget back into the hot days. Somewhere in that process the campaign went back in to learning mode.

Now same ad, same adset, same campaign, I just make a small tweak to some text on one ad and then I let the learning continue... I get "learning limited" within 24 hours.... whereas that same setup for 2 months was delivering more than 50 conversions a week continuously.

How do I recover and get the campaign running again