Need help with dog

So my son brought home some dog food that his friends mom gave him. It was the dry food, I stopped giving that to him because it gave him diarrhea and/or he would constantly throw up or he would be constipated. So I researched other foods and saw that I can give him rice with frozen veggies. When I started giving that to him, he’s had absolutely no issues.

So Friday when he brought it home, I gave him just a little. I figured since it’s been a while, it should be ok. Nope. All hell broke loose. He threw every last bit up in a glob of slime, he started shitting and it had that nasty slime.

So I put him back on his rice and all day today he’s had diarrhea and a little blood. I don’t have any money for a vet unfortunately. He’s healthy but just seems he has a sensitive stomach. I feel bad for going against my judgment and giving him that crap.

My son said when he told the lady what his dog eats, she rolled her eyes.