Large, red sore on my dog's abdomen?

Try Dermavet, it's antiseptic wound healing cream. (Made for animals). http://www.drugs.com/vet/derma-vet-cream.html You can buy it at most pet/veterinary approved food stores and ofc at a vet. (without having to pay for a vet consultation you can buy it) No prescription required.

Sorry, we can't examine her over the internet and no vets here anyway! Part of choosing to own a dog means you've accepted responsibility for providing vet care. A check-up is not VERY expensive....

How old is she? How high is your grass? Where do you live? Could be a bug bite, could be a scrape, could be an abscess from a bug bite - keep her clean, and cool, and, if it starts to abscess (grow a head that looks like a pimple (you could put a warm CLEAN paper towel on it, and trade off with another one, etc. till it pops - - Honestly, unless you live in a tick infested area, it's probably nothing, but why haven't you found a vet that'll work with you to keep your dog healthy? Many vents will cut you some slack, cost wise, if they realize you really care about your animal, and just aren't rich. Shop/ask around, would be my advice. Plus, just keep an eye on it. . She's got a pimple. What would you do if it was you?

People who cannot afford to take their dogs to the vet in even a non-vital emergency case such as this, should NOT have a dog. Either you need to get her to the vet to have her properly examined, hope that whatever it is is benign and not cancerous, or surrender her to a shelter so she can have the chance to be adopted by someone who CAN afford to care for her. God forbid if she should ever be in immediate danger and you can't even go to the vet as a FIRST resort for an examination. *sigh* That theory I have on owners needing a license like a car is screaming loudly in my head again....