It might be that you're killing it with kindness. I never fertilize my herbs and they frequently go without water longer than my guilt feelings can tolerate. But do check the underside of the leaves for anything that doesn't look right. I'm hardly an expert! ;o/

cora

How long has it been since transplanting? It may be suffering from shock - whether it recovers or not, time will tell. Is it in full sun?

When I dig up & pot transplants, I keep plants very moist & out of direct sun until they put out new growth.

HTH

Look along the stem, especially towards the bottom, for scale insects. If you find them, spray them with horticultural or cooking oil.

I transplanted it several weeks ago. It looked healthy for quite some time after that process. All of my basil ends up looking this way. :/

I will check for scales though