One of my pigs had poop like that recently, but it was a result of him being on Baytril.
It took about 1 week for his poops to get back to normal. I fed him poops from my healthy pigs, as Ly&Pigs suggested, this is the best thing, but obviously not an option for you. You could buy acidophalus capsules from a drugstore and open the capsules up and give him a little bit in water twice a day. When my pig was sick, I also fed him 25 mg of vitamin C per day, also by syringe.
Also, the fruit is good but also might be contributing to his pooping problems. Maybe just stick to the veggies until his poops are back to normal. Remember to make feeding changes gradual, that can affect their poops too.
Pigs don't get colds, as someone else has pointed out, they get URIs. If your vet said your pig had a 'cold', I'd say get another vet...
If you weigh him daily when he's sick, that will also help, I hope you have a good scale.