How to help my attacked bumblebee cichlid!

We joined a bumblebee cichlid with a kenyi, both tiny (1 inch or so). The kenyi preceded the bumblebee by about a week, and the kenyi kicked the living bejezus out the the bumblebee. The bumblebee cowered in the corner, so after 2 days of this, we finally got an additional small tank to isolate the kenyi... after intro to the bumblebee, she also killed our plecostomus and started nipping at the silver-tipped sharks, which she had previously left alone. Now the bumblebee is eating, swimming about happily with the catfish, but her injuries are turning blue (?). Eye, back fin, side fin... Does she need antibiotics? Could she spread her illness to other fish? Also, we want to introduce a couple more fish - should we wait until she is fully healed, or is she likely to get as aggressive as the kenyi if she is the only cichlid in the tank? Do cichlids get along with tiger barbs?
Do we dare get her another cichlid pal?