Edema itself isn’t a big issue. Edema in other contexts is a symptom of some underlying issue; but in this case you caused it to happen by forcing fluid into your penis. That increased the pressure in the area and some fluid managed to diffuse through the cellular membrane walls and get trapped in void spaces. On it’s own the fluid will eventually drain out of the area (if it persists or worsens though then that would be a symptom of some underlying issue).
There are some things that can help speed up the process though:
1. Diuretics, like Caffeine, induce your kidneys to remove water from your body. This will lower your blood pressure slightly, and that will increase the diffusive force driving the trapped fluid back into your circulatory system. So have a shot of espresso or a cup of coffee.
2. Reduce your Sodium consumption. Your body tries to maintain a consistent concentration of salt for conducting electrical signals to and from the brain. If you consume less salt the concentration will drop; so your body will remove some water to get the concentration back up to the normal level.
3. Compress the area. This is basically just doing the opposite of what you did to cause your edema. You’re increasing the pressure on the fluid in the void spaces to push them back through the cellular walls and back into your regular circulatory system. Just make sure you don’t try to compress the area too tightly or you’ll cut off blood supply.
Some of the more experienced vets will wear condoms while exercising to avoid edema in the first place. The compression from the condom on your penis will make it harder for fluid to cross the membrane walls and get trapped.