Suggest Remedy For Loose Bowels In 17 Months Old

My child is 17 months old! He had a recent cold which he has got over, however the cattarh lingers a little in his chest which he clears now and then! During and now two weeks later he has loose bowels! He will have 1-3 movements a day ranging in colour and texture! He has had mucus in it too bit thats not everyday or everytime! They range from yellowish to greenish to brown and the smell is awful sometimes! He is drinking water ok, eating ok (although going thru a picky stage) and appears to be playing well, maybe a little tired! I have been to the gp who gave me electrolyte sachets buts it s quite hard to get him to drink it! Please please advise