Wild Leek (Allium ampelpoprasum) is not to be confused with the America (Allium tricocca) which gets called Wild Leek but is in actual fact the Wood Leek. I think I can safely say that what you ate was definitely not a wild leek, as all the leek family have a mild onion taste and aroma. At least the ones I know about, I'm not an expert and there could be some of the leek family I don't know. In fact as leeks are all part of the Alliaceae family (once thought to be part of the lily family), that's a pretty safe bet.
Would you mind telling me where you live or the first half of your postcode? I ask because using the Postcode Plants Database run by the Natural History Museum (www.nhm.ac.uk/nature-online/life/plants-fungi/postcode-plants/) we can discover what plants grow locally to you and narrow it down from there.
I've written a few articles about obtaining edibles from the wild and I always say that you should take a good field guide book with you, and when using your field guide ALWAYS make sure you know exactly what you're picking and NEVER pick anything if you're not 110% certain what the plant is. If you're not sure take a picture and make sure you correctly identify a plant before you ingest it. I don't want to sound like a mother hen, but what you ate caused some worrying side effects, but they could have been so much worse! Never assume what a plant before you eat it, make sure you know! There are so many look a likes in the plant kingdom and the looks a likes are the ones that invariably have the toxic or poisonous side effects that it just isn't worth taking the risk. The Umbillifer family springs to mind with the poisonous Hemlock (Conium maculatum) looking like so much like Cow Parsley (Anthriscus sylvestris) to the untrained eye.
On most of the listings for leek on the Plants for a Future website it says "Although no individual reports regarding this species have been seen, there have been cases of poisoning caused by the consumption, in large quantities and by some mammals, of certain members of this genus. Dogs seem to be particularly susceptible" It doesnt mention the side effects you and your father experienced.
If you can send in a photo or post it on here that would be useful and will help us try to identify what you actually ate. If you cant figure how to get the photo onto the forum, email it to me and Ill add it for you.