I keep rats as pets too. Don't bother separating them, it'll probably be worse for them in the long run, they'll miss each other's company. What kind of bedding do you use? Sometimes changing the bedding will help relieve the symptoms a bit. Also, you can put a couple of drops of echinacea in their water, I've heard it can help boost their immune system. Although I did try this with a couple of my myco-rats and it didn't seem to help. You can take them to the vet if you are concerned (and I suggest that you do take them if they seem to get a lot worse and are in obvious distress because it might be something other than myco if it gets bad). The vet will probably prescribe baytril and doxycycline (antibiotics). But I had the same problem with my first rats and once the course of antibiotics was over, the symptoms came right back, and the drugs can be pretty expensive (I paid over 100$ for the vet visit and a 3 week course of those 2 antibiotics).
If it's any consolation, those same 2 rats lived for nearly 3 years and never seemed the worse for wear because of their myco, and when they finally had to be put down, it was because of old age complications (tumours and paralysis).