I would do a 50% water change today and another one tomorrow and then start the Metro on the 5th. Just follow the directions on the metro IDK how many grams you will need.
The reason I told you to do what would amount to a 100% water change with a day of rest is because it's not advisable to mix EM with Metro. While EM is an effecitve antibiotic at higher Ph levels you should concentrate on treating the most severe issue first. The HITH is a more serious threat at the moment an Metro will be more effective than EM in this situation. Fin rot can be helped by the clean water. After the HITH is adressed any secondary issues can be adressed. Aquarum salt can be used in conjunction with Metro also but do to the fact it is a planted tank I did not recomend it and don't think it is necessary at this point. If you would like to add salt only do a half dose of 1 tbl spoon per 10 gallons of water.
The Advice That Tom gave you if you have not done that and there is still issues would be exactly what you need to do. His advice is spot on correct and I would recommend it.
I did what he said. The 2 50% water changes plus the metro. It seems to be getting better. The fin rot seems to have gone away. Still some holes in multiple fish, continuing to treat with metro. Any other advice? When should I do another water change?
Just follow the instructions on the Metro package, it is important to do exactly what it says. Once the HITH is cured there will still be scarring form the pits, this is common so don't be concerned. Post an update when you finish the metro treatment I would do three treatments with the waterchanges as instructed on the package.