You aren't being very clear. When was the trip? Was the trip a month ago and then afterward he stopped pooping? Or was the trip recently, and you have two problems, the darting away and the constipation?
Most problems like this are indicative of bad water quality... you should get him a bigger aquarium. A bowl is not sufficient. He needs at least 2.5 gallons, preferably 5 gallons, to be healthy... he probably hasn't pooped because he is stressed. The pea is helpful to get him to poo, but you still need to work on what caused it in the first place.
The bad water quality means there may be ammonia and nitrite in the water. Get liquid test kits for ammonia and nitrite. Test the water. If they are above zero, this is too high and you need to change the water frequently until it goes as low as possible.
