Thank you for your question. Swelling can occur for 1-2 hours after Botox injection. However, this may be due to your microneedling treatment. I recommend following up with your injector for an evaluation and possible treatment. Best of Luck!
This is just my clinical impression but I think the injection may have caused atrophy of the muscle, leading to the defect. This could be completely addressed with fat injections. Fat can easily build up the depression, restoring volume to this area. Should you seek botox injections...
I would recommend you discussing this with your provider in detail as some practitioners prefer to give Botox prior to resurfacing with ablative or fractional laser and some prefer to treat after resurfacing. It works well in both cases as it helps to relax the dynamic creases of the face...