Hello again, Kevin and thanks for your very helpful reply.
From your description of his symptoms, it's possible that your lawn or soil is being treated with a chemical that is toxic to cats or to which Pepe is allergic. He also may have an allergy to grass, itself. It's also possible that he didn't just pass out, but may have had a seizure. Here is more information about seizures in cats, but all symptoms may not be present for each instance/each cat: CLICK
If he vomited grass before passing out, the vomiting in this case, could be associated with a heart condition triggered by the vomiting, resulting in fainting.
Because this happened twice within two months, it would be a good idea to have Pepe seen by his vet for a hands-examination, blood work/urinalysis, to find out if there are any abnormalities. Also, of course, keep him off the grass and prevent him from eating it, which you already mentioned you're doing, in your initial question. If a seizure or seizure-type condition is suspected, your vet may refer you to a veterinary neurologist who wil have the specialized equipment to check him out more thoroughly.
I hope all will be well with Pepe and please let me know how he's doing and what the vet tells you. Thanks!
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