I saw you query little late... I am not a vet... but I will try to give you details on this deadly virus.
In you I noticed few things:-
1. The breeder from which you bought puppy is not a good breeder at all.
2. 38 days old is too young to separate from his/her mother.
3. I am not sure whether your puppy got colostrum from his mother or not. Because Parvo at this age is not possible (normally) if a puppy gets colostrum from his mother. Colostrum gives puppies immunity to fight with several diseases.
4. For a puppy age less than 1 yr, whenever you found bloody stool & bloody vomit, contact a good vet without any delay. Don't take it easy, when you find blood in stool & vomit.
Parvo is very very dangerous virus for dogs especially having age less than 1 yr. And it effect Rottweilers most.
I am saying it all from my own experience. I am having a female rott & she got parvo @age 7-8 months even after proper vaccination. But my quick response, vet's effort & god's grace saved life of my sweet girl. Now she is absolutely normal & at age 11 months.
Please take care few things in future.
1. Don't take any puppy before age of atleast 8 weeks.
2. Proper vaccination on time & by a good vet.
3. Blood in vomit & stool can be parvo (90%) so don't wait for a single moment.
4. Keep wood & other infectious things out of reach of your puppy.