Dog is sick after heart worm shots!! Please help.?

About a month ago I adopted an APBT from a Bully rescue farm. When I took him for his checkup he tested positive for heartworms. About a week later he received two shots for his heart worms, the shots were divided in an 24 hour time span. The vet told me that he would be sick for about a month, and may be extremely tired and eat less. It has now been two weeks since his shots and he was doing a lot better he was finally gaining energy and was starting to eat better. BUT yesterday I noticed that he was vomiting quite a bit, and making a hacking noise every now and then. THEN today, I can't get him to eat anything at all. He won't touch his dry food or wet food. He loves meat, and he actually ate one. Almost immediately he vomited it up. I am so worried about him, he cannot keep anything down. ALSO when I took him to use the restroom today he took a number two and then walked in circles and tried to take another number two but instead a mucus like substance came out, it had a reddish tent and I was worried it was blood. My vet is about a hour away and I just wanted to check with other people who have had animals that had to get this shot also and make sure this is normal behavior or not before I took him down there. I would rather be safe, then have them look at me like I am dumb for freaking out. He is still drinking water regularly but almost a minute after he vomits a substance that looks like slobber. If anyone has any advice that would be greatly appreciated. I will be calling the vet first thing in the morning.