Now looking at this lesion, we do need to tread with care. The top looks abraded or a possible mild dermatitis, but I agree that it does appear raised as well. Still, it is possible that this is just tissue reaction as opposed to a possible growth.
Therefore, we'd want to monitor this closely while we use supportive care. Now this is notoriously a difficult area to treat topically, therefore you will be limited with how to treat it at home (most dogs will lick off creams just as Pepper did). That said, there is no visible infection here and therefore our mainstay treatment at this stage would be to cleanse the area. To do so, you can bathe this 2-3 times daily with a mild antiseptic. Since we have that licking risk, we'd want to use either dilute chlorohexidine or salt water (1tbsp to a pint warm water). This should be done after meals to help remove any food or saliva (which is full of bacteria) from the site. As we do this over the weekend, we'd hope to see the inflammation settle and the puffiness hopefully reduce.
If we do this and it doesn't by Monday, then it'd be worth a check with her vet. They can assess the lesion, determine if it is a growth or just swelling from soft tissue trauma, and potentially start her on dog safe anti-inflammatories (ie Metacam, Onsior, Previcox, Rimadyl, etc) to reduce any swelling here. And if infection is a risk, then oral antibiotics are usually more successful then topical ones.
Overall, with this lesion's sudden onset, soft tissue irritation secondary to abrasion of the skin is our top suspect. Therefore, the above should help reduce that. Of course, if that swelling isn't settling over the weekend, then we'd want to err on the side of caution and have it checked to rule out anything sinister and get oral treatments to settle it if need be.
All the best for Pepper,