Are your good days and bad days opposite ends of one scale?
David Watson, Lee Anna Clark and Auke Tellegen · Development and Validation of Brief Measures of Positive and Negative Affect, JPSP 54 · 1988
B · Replicated, size uncertain
Positive and negative affect are separable dimensions, not two ends of one. A day can be high on both. The PANAS measures each with ten adjectives over a stated timeframe, and the timeframe matters: state and trait versions are different instruments.
ProbeRate ten adjectives for today, positive and negative separately. Track both for a week rather than computing a single net mood.