Never had a puppy- health care concern/question?

I've never had a puppy and I don't know any of the weird things that puppies go through when growing and naturally I'm freaking out at everything thinking he's sick and needs to go to the vet. He's between 6 and 7 months old and a medium size breed. Currently sitting right at 30 pounds.

When we first got him from the shelter a month ago he succumbed to kennel cough and had to be on antibiotics (ampicillin) for 7 days. At the end of the 7 days he was better but still coughing, running nose, etc. so they put him on 10 days of doxy. He quickly became a rambunctious, normal happy pup. Then, 3 days ago the antibiotics were done (yay!) and I gave him a yogurt cup over the course of two days as recommended by my vet since he was on antibiotics for so long.

For the last two days he's been sleeping a bit more and eating less. So I guess what I'm asking is is that normal puppy behavior? Do they go through periods of sleeping more and eating less? He ate all of his first meal yesterday, but very little of his second meal and seems uninterested in first meal this morning. He's also become even more velcro. He tries to crawl from the back to front seat in the car to sit on my lap which he hasn't done since he's been well and he keeps jumping in my bed and cuddling up to me in the morning when my fiancee gets up.

I should also mention that even though he slept more, he perked up and was really playful when we took him to my grandma's house for a family thing.

I think I'm so freaked out because our previous vet (who we left because he didn't like to communicate what he was doing to my dog before doing it) said "thirty years ago I would have said this dog had distemper. But, eh, who knows." DON'T EH ME WHEN YOU JUST SAID THE WORD DISTEMPER. But it seemed like when I told other dog/vet tech people that I knew they all thought he was crazy. Hugo has had his initially Distemper vaccine, but not the booster because he was sick when he needed it and the vet obviously didn't want to give a vaccine to a sick dog.

Is this all normal? I'm probably over reacting and I'm sorry I basically wrote a short novel... I just want make sure that if he's sick I take him to the vet!

Reduced activity and reduced appetite for a short period of time, without any other symptoms, is normal. Not just a puppy thing, but a dog thing! Heck, anything that moves and eats will have days where they're more lazy, or less hungry. Perfectly natural.

Warning signs: not wanting to eat for more than just a day or two (including tasty treats), not drinking, abnormal activity level for the dog, any form of discharge from any orifice, fever, vomiting, drooling, abnormal breathing rhythms, abnormal bowel movements, pale/tacky gums, etc., etc.

If you are at ALL concerned, never hurts to visit a vet just so they can tell you, "Yup, everything looks good on physical, no fever, he's looking good!" And if there is something wrong, you'll have caught it early enough for it to not become as serious.

Thanks for the reply : ) I've had 3 dogs and they definitely went through lazy days, but I had never had one outright refuse a meal. He's acting totally normal now an is, in fact, staring intently at the clicker I left on the table so he probably wants treats. I think I just let that vet get in my head mentioning distemper.