Update, since I wasn't sure what the infection is, I treated with one dose of the quarantine trio. He was breathing really heavy one the second day and hiding. The rest of the fish all seemed ok. Most of the bubbles are gone, only two are left as of today and they are shrinking.
However a platy developed fin rot on day 4 and I isolated it in a quarantine bucket with salt and it's doing well. Now it looks like the neon tetras are starting to have discloration on thier fins. Water parameters haven't changed and I did a 1/3 water change today, as it was 8 days after I dosed the trio.
Should I treat with maracyn 2 to address what I assume is fin rot on the tetras or dose the trio again?