A few dots on your fish will be ich, but too many spots to count will be brook. You will be the best person to identify which is which because you’re the only one who can see the fish in person.
Either way, FW dips can alleviate fish temporarily from ich if that’s the case. Best thing you can do now is ich management.
Healthy fish can 100% fight illness. Your best bet is going to be keeping your fish well fed (more than usual) and giving them time to heal. Check out this thread:
https://www.reef2reef.com/threads/ich-eradication-vs-ich-management.188775/
It’s not proven to work. But if you’re willing to try, I’m currently adding Polyplab’s Reef Medic in my tank for ich and all of my fish have definitely shown improvement.