Patience or filler
The dose is relatively low (I use 2.5mg/cc, but up to 3.3mg/cc is usual dose) and the volume injected is correct for small lesions. The atrophy will completely go away in 1-3 months. If it is reallly upsetting to you, a touch of filler can help, or even just stretching the area with saline.
For a pimple, 3 mg/cc seems like a rather hefty dose...
think most people typically use a dose of less than 1 mg/cc especially for the head and neck area...suspect no matter what you do, it'll take 2-6 months for the atrophy to wear off...if it really becomes an issue, some people may opt for injection of a filler into the area...in the old days people used to believe in vitamin E as salvation for the problem...but the real cure is tincture of time...sorry you're having the problem