I found this and wonder if either matches what you're seeing:
Small red spots (especially on the underside of the fish and companioned with flashing and rubbing) could be costia - the protozoan parasite
Ichthyobodo. Sometimes costia will not always show up like this, but rather presents as slime coat changes and perhaps some blueness or blackness to the fish. A clear diagnosis sometimes requires a microscope.
Costia should be treated with Rid
ICH or Quick Cure. Though it has a short life cycle, it can be quite hard to treat and treatment requires several applications.
If the redness is in the form of blotches or red streaks, the fish may have an internal bacterial infection, usually caused by gram negative bacteria such as
Aeromonas or
Pseudomonas. Often the redness can be found at the base of the fins. Treat by feeding antibiotic food (Medi-Gold preferably) or if the fish is not eating, use a full spectrum water antibiotic like Maracyn Plus or Triple Sulfa.