How do I treat my rat's bumblefoot at home safely and effectively?

From these photos, there is definitely some swelling, and possible ulceration. These are definitely signs consistent with bumblefoot, also known as pododermatitis. This is typically caused by increased pressure on the feet and results in bleeding and pain. This can unfortunately spread to the tissues such as muscles and tendons below, so I still recommend having Dobby looked at by a vet, just in case surgery or pain medication is necessary. Because the condition is caused by pressure on the feet, I recommend making sure that Dobby has soft, and very clean bedding as dirty bedding can cause an infection. You should avoid scratchy materials for bedding. Vetericyin ointment is okay for cleaning the area, you can also apply SSD (silver sulfadiazene) ointment to the area after cleaning. Dobby should definitely visit a vet if the condition continues to get worse over the next few days. I hope this helps!