NEED SOME ADVICE!!!

of coarse i need advice, or i wouldnt be posting, but I recently did a tat on a guy, it was his name in block hebrew. I actually used full disposable that a friend provided, I used 7liner and 11mag for shading. anyways, after the forth day, the thing looks like a dried up bowl of oatmeal, if u can understand. This is the first tat that ive done that has done this, Im woundering what could it possibly be. My machines are tuned the same as ever, needle depth was not too deep, i actually use my tip as a guide. I barely can even see the tip when it is running. The same for shading, the needles are barely noticable when running. I dont run the amps that high at all, liner was set at 8, shader was at 9.5. He is taking care of the tat, I see him on a daily basis, and his other tats that ive done healed and peeled fully around 2 weeks. what should i consider as the factor of the results of this? Was it me? could it possibly be him? Im scared now, because it looks terrible. Fixable, but for now terrible.

SO MANY details left out. im just an apprentice, but some questions come to mind.

1. sterility - steril environment? steril tools, setup, needles, machine, etc?
2. old ink? where is your ink kept?
3. disposables are tricky, is this your first time with one?
4. tracking with disposables is tricky, did you use a loope to check the performance of your needle, how its tracking, etc?
5. the mag could have been your issue, going over and over and over try to pack that ink in will cause a chumming of the skin, which will scar, and also look like hamburger or oatmeal as you say. shading and filling should be done in 1-2 passes anymore will result in dangerous results
6. proper aftercare - did you inform your client to use noxema on their tattoo? haha i hope not. hopefully you used industry standard disinfectants throughout the tattoo, and taught them how to take care of their new tattoo.

so many factors, and i hate to say, but if you have these concerns, which is a lack of confidence, you probably shouldn't be tattooing. no pun intended but this industry requires confident, competent, and responsible people that take all these things into consideration for each client. please seek an apprenticeship. your probably a great artist, so think of it like that. great artist, tons of potential, but lacking technical skills like safety, application, and care. best of luck!