You may be dealing with the effects of the imidicloprid treatment. If you google imidicloprid phytotoxicity, you will get many articles on the topic. It depends on your application rate, and the causes are not fully understood, but this might be the culprit.
I've been reading up on this recently because I might be grappling with the same problem. I made a deal with the devil to save my peppers from aphids, and am now paying the price. Good luck with your plant. Here's hoping both yours and mine will make it through the winter.
- Trout
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