I do regular Yoga 3-4 times a week (for 4-5 years now) and had no health issues before I flushed and am 38. I've now produced ~1500+ stones from 6 flushes. My largest stone 40mm came out in the last flush! I also produced some sort of liver flukes (parasites) on the 4th flush.
I know 10 people I have recommended the flush to and they have had similar experiences to me which are all good. I would suggest you contact Andreas Moritz to ask him what caused the mucus / foam mouth issue.
I have documented all the info I found and what came out of me on a forum for health and awareness. If you google "flushing the toxic stones from within the liver" you will find all the information that I found on the liver and gallbladder.
I would suggest the foaming mouth is either a reaction or another health issue you need to address. Andreas Moritz can easily be contacted via his website for his advice.
health and happiness