This all happens to me too, again it is good to know it's not just me! I am generally very healthy yet colds for me last a lot longer than they do for others.
I salivate a lot and then the irritation in my throat forces a swallowing reflex. The constant swallowing gets my stomach excited for food that isnt coming and so it gripes.
I guess there is nothing we can do and at the end of the day one can live with it. The problem is it prevents me sleeping and so recovery is delayed because I get no rest.
I have found there is nothing particularly effective but sucking cough sweets or extra strong mints reduces the swallowing reflex by slightly de-sensitizing the throat. The small amount of 'food' in the mouth controls the salivation a little and reduces the stomach's reaction.