Dog Heartworm Treatment

Its only 4 weeks old and i some symptoms that he has is a bloated belly and he eats a lot and even when I try to help him poop he wont hes only pooped twice in 2 days, i heard these are some of the symptoms to round worms so i was wondering if i could give him the medicine because of his age?

I just got a new kitten last week, and the person I got her from had 4 cats that gave birth. One of their cats kittens would always die, from every litter it ever had, and one of the symptoms that those kittens would get, is they would start getting little bald patches. When my kitten first came home, she was perfectly fine. On the second day she was here, I noticed that she was sneezing every few minutes. A few days later, I noticed a little bald patch on one of her paws, and then I noticed a slightly bigger bald patch on her chest. She also has two smaller bald patches on two of her toes on her back feet (the two inner toes). Also, a few days ago, she woke up and couldn’t open one of her eyes. She had gunk in it, and we had to wipe it out for her. I think I saw what looked like worms in her butt. I also have a dog that she is always playing with. Somebody please let me know if they know what this could be, or if it is contagious, so I can keep her away from my dog!