I don`t know if anyone has already mentioned Imodium Melts. When the bathroom issues strike (And they will !) it works super fast, considerably faster than the capsules. It was mentioned in a post some weeks ago ,that in high doses this could work on the opioid receptors in the brain. I actually asked my Neurologist the question ” How much is a high dose” He told me that if I were buying the Melts (Which are on average around 60p each here) I would need hundreds of pounds to cause any sort of meaningful effect. He would not be drawn any further on the amount, or what he meant by “Meaningful effect” In retrospect i hope he did not think I was a candidate for spending hundreds of pounds on a diarrhoea product. Anyone who takes huge amounts of these type of product must be bunged up for all eternity. Ouch ! Anyway… as you are going to be travelling soon, , I thought I would mention it, as a long haul flight is hardly the best venue to be struck down with this kind of problem. They really do work within the half hour.
I hope you are doing OK and not suffering too much.