So long as the bruise is no longer spreading* and the pain is subsiding, it's probably OK to just keep an eye on it. Even given perfectly, bruising can happen, as local tiny blood vessels can get squished: there's no reason to be concerned about the hormone pellet, which will still dissolve in its own time.
*over a few days, the discolouration around the bruise - mauves, blue, possibly green and yellow! - will spread, the colours should be fairly dull, not bright, that's normal, but if it looks like there's still active bleeding going on in there, it's not normal.
1. So long as the bruising progressively looks less 'fresh' each day, should be OK.
2. So long as the discomfort is reducing over time, should be OK.
3. But if you are at all worried, get your GP or the practice nurse to take a look.