Greetings, and thanks for the question.
There are many causes for diarrhea in the goat, especiually the younger ones. You mentioned that he was recently dewomed, do you know which typed of dewormer was used?
There are also many types of species of internal parasites, but young goats are especially vulnerable to a type of parasite called Coccidia. Coccidia are not worms, but are an amoeba like organism that attaches itself to the intestinal lining where it causes inflammation and inhibits the normal absorption of fluids, which normally causes diarrhea, and if the infestation is severe enough, can also lead to weakness, and even death if not treated appropriately. Unfortunately, the majority of dewormers will not affect the organism. Coccidia requires a different type of dewormer known as "Corid" which is a liquid given orally. This product should be available at your local feed store. I usually recommend a dose of 2.5cc given orally once daily for ten days.
However, to be sure that this is indeed your goat's problem, the best way to go is to have a fecal analysis done at your Vet's clinic. If you don't have a large animal Vet, chances are that any small animal clinic would be happy to run the test for you. Just try to get a fresh sample and keep it cool until you can get it to a clinic. I would recommend that you do this soon, as Coccidia can multiply at a very rapid rate.
Also, it's also a good idea to administer a probiotic (such as "Probios") to help keep the gut flora healthy.
Attached is a link for you that goes into more detail thak I have described here.
So I hope that I've been of some help, and please let me know if you have any further questions.
All the best, ***** ***** you find the time, please let me know how your little guy is doing.