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That's definitely a scary situation to be in!

I can't say for sure whether or not your mom did give you this without your permission, but it sounds like there is at least a possibility that she did. This seems sketchy to me. For example, you said she gave you shots before? Were these prescribed by a doctor or were they something she came up with herself to try and give you? If you don't have a prescription she shouldn't be injecting you with anything and that can cause your body more harm. It's important for your doctor to know if she's giving you unauthorized medication as it can interfere with future treatments and diagnoses.

I don't know if you have any money of your own but if you do, I'd start getting your own medications instead of taking them directly from her. There are over the counter medications for different ailments that you can get without a prescription, and you know they haven't been tampered with. No matter how much she cries or tries using scare tactics such as talking about your grandfather, I'd stick to your grounds and refuse to take medications from her directly when you're sick. Since she possibly did this unknowingly, even refusing water may be in your best interest.

Are you able to speak up to anyone such as a teacher, doctor, or other trusted adult about what your mom is doing? They would have to report it and investigate, but your mom shouldn't be trying to treat you with things like this without your consent, especially if the things she is using may be causing more harm than good. It doesn't necessarily mean you'll be taken away, but she may have a better eye kept on her.

I'd also go to the school nurse about your throat at the very minimum. She can look and see if there are any visible signs of damage to the back of your throat such as redness or inflammation. Are there any white spots in the back of your throat? That may mean strep. If your mom will let you, I'd go to the doctor or an urgent care to get your throat swabbed for a strep test, just to be on the safe side. Hopefully it's something simple like strep that can be treated, rather than anything more sinister.