Keeley is one sick puppy

Here's a picture of Keeley resting with his grandma because he's been very ill the last few couple of days.
Late Monday night, I took Keeley outside for his last potty trip before bedtime. He was sniffing around for a spot and then he stopped in the back corner and started eating something. At first I didn't think much of it because I figured it was just rabbit poop but soon I realized it had to be something else and went to investigate. Keeley's reaction as I approached him confirmed my suspicion that it was definitely something that he should not have. So i grabbed him and reached into his mouth to try to pull out whatever it was. I was too late though and all I could get out was a part of what appeared to be a foil wrapper from a Hershey's Kiss.
Okay, I know there's a lot of trash always blowing around in the neighborhood. Ridding the yard of empty potato chip bags, Hostess cake wrappers, plastic grocery bags, and newspaper is a daily task. But how the heck did a pile of partially unwrapped Hershey Kisses get way back into Keeley's yard? It just doesn't make sense. Anyhow, I was pretty confident that there couldn't have been enough there to make him sick and so we went to bed.
Right away on Tuesday morning, I could tell that something was wrong with Keeley. He didn't want to get up. Then I made him breakfast and he didn't want to eat it. He didn't want to go upstairs and knock on his grandmother's door like he usually does. All he wanted to do was to lay around and be petted.
Eventually, he did eat part of his breakfast. But by the time I got home from work, he had thrown it all up.
For dinner I made him rice and burger since it was obvious that his tummy was upset. He did eat it but then 10 minutes later, he threw it all up. And later, he threw up a few more times outside. All he wanted to do was to rest and be petted.
I was woken up at midnight by the sound of Keeley throwing up again. And again. And again. And again. And again. And again 19 more times through to the morning.
Keeley was not himself. He wouldn't make eye contact and his tail and his head were down. He looked so weak and completely pathetic. I was so worried about my little baby boy.
When morning did finally come, we took Keeley to see his vet. I had to carry him to the car and into the vet's office because he couldn't even walk.
He spent all day Wednesday at the vet's office. He got his blood work done. He got his electrolyte panel done. He got x-rayed. He was given IV fluids. He got an antibiotic injection and an anti-vomiting injection. By the end of the day he had begun to act a little more like himself and was happy to be going home.
I stayed home with him all day today. He took his medicine and drank a little water but didn't feel like eating anything till just about 35 minutes ago. Finally, he ate a little rice and beef and a few rice krispies. And so far he's managed to keep it down.
What we think is that Keeley got into some poison. Maybe a neighbor put out some poison to try to kill the mice, squirrels, rabbits, raccoons, birds, or possum that live behind our garages (and in many of the garages on our block). Or maybe Keeley killed a little animal that had eaten poison. Who knows?
At least he's beginning to feel better now.