I have a somewhat bad feeling about that.
Mating wounds? What? Causing problems after 6 weeks? Not likely.
When there were wounds it is more likely girls were fighting.
A pet shop that sells pregnant, injured animals where there are fights between rabbits and nobody does something about it? Keep away, don't buy (or even get replaced) anything there, at least not without someone with a lot of rabbit experience at your side.
I don't know craiglist, but our local equivalent is the best way to find breeders and buy rabbits. I can weed out bad apples after a phone call most of the time (both sellers and customers, I sell this way too)
I don't understand why backyard breeders have such a bad reputation (I'm one, but not exactly for pets), the ones I know care first for health, second for their breeding goal (character, breed standards, meat production...). Sure, there are black sheep, but I'd rather buy directly from a breeder and speak to him than via anonymous pet shops.
Shelters may be the best source, if they are good (I guess most are, but I've read terrible things about ARA shelters that are more like a hoarding operation and germ spreading institution, local shelters here refuse to deal with rabbits since it is not easy), get a second opinion anyway.
Do not buy a rabbit out of compassion, or because this one is sitting sweet, cuddly there while all others shy away (-> very bad sign). When a rabbit has wounds, or other problems, it needs to get treated. That's a responsibility that is inherent with caring for an animal.
That can be expensive, but you can do a lot with some help from here and information from the net, but you need to give information about what the problem is as soon as possible, rabbits hide those pretty well, when you notice at last you have to act very fast. You may have to wash off poop, clean wounds from puss, force feed a rabbit, watch their teeth and claws etc.
If you are not sure that you're up to that do yourself a favour and take a few months to think about it, read a lot here and on other sites, get in contact with people who have rabbits.
Granted, getting a injured, pregnant, very young doe of questionable heritage and prone to problems is a hard thing to pull through, even for experienced people.
Also granted, you may not know your first bunnies age (where did you get him?), it really could have been old age.
But having 2 rabbits die on me in short time I would apply Ockham's razor and consider that there may be other problems, closer than the breeder or the pet shop, that you might not be aware of.
How were they housed and fed? Are there any other animals around? I reckon you don't have access to a rabbit savy Vet?
Uhm, since I'm not a native english speaker I can't tell where you come from by the way you write, telling us your general location would make it easier to help you, there are different problems in different regions (deseases, toxic plants, predators...), maybe someone can recommend a good vet, or help you more directly.
At least, before getting another rabbit, gather information about it, make some pictures (from every angly, also privy parts etc.), and ask for opinions here.
so if buying a rabbit from a pet shop you want to see how they are kept, give rabbits a thorough health check before buying (listening for rattly breathing, clean eyes, ears, nose etc, no urine scald and such like). Well kept rabbits are easier to ***, handle and sell. Many pet shops understand this, but some do not. It shouldn't be that hard to winnow out the poorer quality shops.
