Another anti-fungus spray is diluted hydrogen peroxide. You can water with it or just mist the surface, and/or spray leaves with it.
I don't know about spraying with peroxide and baking soda very close together. It might be OK, might not be, or might nullify the effect of either or both.
I think that there would be no downside to alternating chamomile tea and peroxide. Or just pick one and use it until it seems less effective, then try the other for a while.
0.2% hydrogen peroxide:
dilute "drugstore" hydrogen peroxide by 1:16 -
1 tablespoon per cup of water
2 ounces per quart
1 cup per gallon
Preventing fungus, no matter how hard, is probably easier than curing it once established.
P.S.
You should get some improvement just by keeping the soil surface drier. Less frequent, heavier watering helps with that. Air movement (a fan) or lower humidity would help dry the soil surface somewhat. Bottom-watering (if convenient) should help.
I think the best way to get a dry soil surface is to top-dress each pot with relatively coarse bark nuggets. Gravel or pebbles ought to work too. Very coarse Perlite should stay a little drier than straight potting mix.
Besides being drier and therefore less fungus-friendly, top-dressing can make the exposed surface less "organic" in the sense of less digestible fungus-food exposed to spores in the air. If you have compost in your potting mix, that feeds fungus like candy. If you use organic fertilizer like fish emulsion, that also provides fungus with easily digestible food.
If you ever re-pot the herbs, using a faster-draining and less-water-retaining soilless mix helps.
Probably any soilless potting mix is less fungus-friendly than any kind of potting soil, or any mix with any garden soil in it.
