Clownfish Infection or Injury?

I just posted about finally getting my first tank set up with two clownfish. I got a bonded pair but the pet store kept all their clowns in one tank so the male may have been getting bullied before I got him bc one of his fins is a little tattered

Behind that fin I just noticed a small purplish spot and I'm worried whether it could be a bacterial or other infection.

Does anyone have any idea what this could be?

In the meantime I've begun treatment with melafix just in case.