Till then keep to things that are easier to digest, if only to get rid of (or at least lighten) the diahrrea in the first place and let your system recover a tad--diahrrea flushes out a lot of the bacterial cultures in your intestines (so i've heard) and so eating really easy to digest foods helps give it a chance to recover.
Unfortunately the easiest is white rice and bread, but you're trying to get off the overprocessed... Brown rice (not wild!), pasta, oats (instant is easiest, but again very refined--rolled is next best) are also easier on your system. I'm not saying eat ONLY this, unless you're desperate to make the diahrrea stop, but it should alleviate your problems a bit if you eat a bit more of it for a few days...
Actually, all things considered I'm not surprised you're getting these symptoms--going 100% plant based as well as cutting out refined flour is a huge spike in fibre intake! Going off caffeine can't help. Not that I condemn this, just saying: I wouldnt worry too much, it isn't unexpected, it should go away.
Good advice on eating/drinking habits while you have diahrrea: http://www.healthcastle.com/diarrhea.shtml
no matter what the cause of it is, you don't want to get dehydrated *nodnod*