Hello, just let it be known this is my first post on here! I only found out there was actually a word for fear of 'you know what' (after reading around here, I am gathering the dreaded word is not commonly written although it doesn't bother me personally to read it, I will be sensitive to other eyes) about a day ago. I am not such looney after all.
Anyway, considering you were on a bus I would presume travel sickness, and since you weren't in CLOSE CLOSE contact with them or the..er..yeah, you would be fine if it were something else. Breathe