I very rarely get bumps after injections, so a swelling that takes 2-3 days to go down, could it be this ? How long have you had it and how big is it ?
If you suspect you have lipohypertrophy problems then it's best to avoid that area until things improve.
I've had lipo problems in the past and more recently before moving over to a pump, apart from the visual effect it can also make insulin absorption more erratic and bg levels unpredictable, there a short write-up on the community pages of DCUK about the condition: