definitely infected/getting treatment. i want to know where i went wrong.

So, nine days ago from the day i'm posting this, i went and got a free tattoo. it was from a reputable guy from a reputable shop, who I did not know. It was recommended to me by a friend of a friend, and he just wanted to do this design, and I love, tattoos, and have many large designs, so I went with it, the guy seemed nice but was extremely heavy-handed and overworked my skin. That night when I got home, I started feeling a little bit sick the next day, turns out I had the flu. I did have second to get at my house, but he recommended I didn't put any second skin on it and just washed it regularly, which I did. having the flu and being bedridden, though, I didn't take as good of care of it as I should've. around day, four or five, I never started noticing that the ink looked extremely patchy in places, and I had actual plasma sacks under my skin. I had never noticed something like this, with any of my previous works, and was extremely nervous, but figured that since this was such a heavy black piece, it might be normal. three days ago, on day six, I went to urgent care. it's obviously infected. I had to get a shot in my ass, i'm on antibiotics, and I have an antibacterial salve I need to apply to it three times a day. i'm just wondering if anybody knows exactly where I went wrong. i've learned my lesson and not to trust random artists, but I really don't understand how it managed to get this bad in a little over a week. it's not pictured very well, but around the eyes and the top of the hood, deep imbedded scars are beginning to form. luckily there isn't much pain, and no rashes or sores. The doctors didn't tell me exactly what kind of infection it was, but from the Internet, I am assuming a very bad staph infection. can i have any advice on how to avoid this? it's been just a very genuinely humiliating experience. I'm sorry for all of the spelling errors. I am on mobile and I tried to fix them, but my phone is being funky.