Well first, Welcome to the site. Please enjoy your stay, A Complimentary gift basket will be sent to you within two to eight business days.
Second, I don't have a dick. I won't ever have a dick. But I can safely say that injecting things into your dick is a FUCKING BAD IDEA HOLY SHIT. Now, I'm not a scientist, nor do I know biology very well, But it really sounds to me like injecting water or saline into the schlong could result in horrible pain, intense discomfort, And potential injury. I mean- You even said it got to a fucking NINE on the pain scale. Granted I don't know if your pain scale is one to ten, or one to one hundred, but nobody uses the one to one hundred scale anymore.
I genuinely like the scientific attitude about all this, I really do. But the human body really isn't a great dummy to experiment on. Especially if your experiment is injecting water into your schalldämpher in an effort to expand the cock. Now this next part might just be my instinctual fear of sharp things, But at what point did you think this would be a good idea? It sounds like something Pinhead would do. I really dislike kinkshaming, Especially given my wide array of kinks, but This is NOT a good idea, And any further 'testing' would be a terrible idea. Keep the dong strong, Don't inject fluids into it.
and yes, this was also a personal challenge to try to use as many different words for penis as I possibly could.
Well, I feel for you, trust me. However, there aren't that many users here who practice scrotal injection, so don't expect a lot of advice on the subject. I for one am also lacking in the necessary experience, so you may want to stop reading now as I probably won't be much help.
From what I know about human anatomy, the water you injected can take anywhere from minutes to days for your body to absorb it. Perhaps give it some more time. As for infections, it's possible with your method, but you've taken some steps to reduce the risk. If there's pain, swelling, and/or discoloration seek medical attention immediately.
My knowledge is just basic health knowledge as it applies to the human body in general, so necessary specific attention may be needed for your situation. I hope some bit of this helps. Sorry for your problems, and best wishes for a successful return to normalcy.
Fill 'er up!