When I did my first flushes my anus burned very painfully so I began coating my anus, outside and a little inside with olive oil and that helped a lot. I would do this evey time I had movement. Later on I found that I needed to throughly wash my rectal area after each movement and that stopped the burning too. I've done more than 60 cleanses and don't usally have burning any more so maybe that problem will get better.
Lately I have been using 2/3 Epsom Salts and 1 tablespoon milk of magnesia in 1 cup of water and that has helped with the cramping and burning of my upper intestine when I take the laxative. I some times take just epson salts on the morning after. I have also found that including 1/2 caplsule of Cascara sangrada helps the flush.