Maybe you caught some bug thats affecting your stool. Also it could be the cold relief medicine thats caused this issue. Consult your GI and get your blood tested if you think its serious. If not try altering to a feel good diet. I'd avoid bananas during cold as they tend to aggrevate it. Drink lots of fluids and electrolytes to keep replenishing the body.Also you can add/increase fiber supplement dosage or try anti diarrohea meds like imodium/lotomil.

Green stool is simply caused by faster transit through the gut. Lots of us have reported that having a cold causes GI disturbances for us that can last a few weeks. Raj’s suggestions of fiber (like psyllium) and/or Lomotil/Imodium may help - be careful to stay hydrated. I disagree about the bananas, though: many people find them helpful for diarrhea, and the potassium that they replenish is the first electrolyte to be lost in diarrhea.

So more people have noticed that colds cause problems in the gastroenterolic tract. Interestingly, I figured it was so. This time it takes longer but the cold was stronger.

I had the cough for almost entire winters. So persistent it never went away though I did a very course of anti biotics but it stayed. So I just cut off all foods that would aggrevate it. As for bananas it does have fairly high electrolytes but it seem to aggrevate my cold even further so I eat them only during daytime.

It looks like a cold and similar, closely related to gastroenterological problems, and it's hard to know what it is. I got cipro for throat infection this time, but he did not stop diarrhea.