The first antifungal I tried which was very effective was nystatin which binds to ergosterol in the cell membrane (ergosterol is like cholesterol, but seems to be only found in fungi). The major change in symptoms from taking this drug which never reaches blood is quite conclusive for me.
Wrong. Gastritis is stomach inflammation which means the stomach's immune system is responding to something injurious or to an infection. Have a look on wikipedia about inflammation.
I became terribly sick about a year and a half ago after ingesting a really cheap chinese herbal tea that was supposed to help with jaundice (because I have that, but no other liver problem). And blood tests indicated no change in bilirubin levels.