Phil
Believe it or not, you're probably doing yourself more harm than good by taking Immodium. I can empathise with you to a degree regarding the trots, but, immodium only suppresses the symptoms and provides temporary relief, it is not a 'cure' per-se for whatever it is that's wrong with you and your good lady.
The 'cause' is more than likely the change your body experiences as a result of going from a relatively benign climate to the heat of a Turkish summer. Most people attribute a dose of the runs as synonymous with being in a foreign land, but, the cause is more to do with weather (in and out of heat/shade/air-conditioned apartments) than it is with food etc.
The best advice (from my doctor) is try to ride-out the symptoms in the same way you would a cold, the advice I received was "take suppressants, the symptoms will last a couple of weeks, avoid them and it'll last 3 - 4 days"!! It's worth noting that you can over-hydrate as well and this can play havoc with your metabolism!!!
regards