Ouch, definitely get your scalp looked at, there might be something you can put on the worst bits to ease the pain/ help with healing.
I'd suggest getting better photos as well, as the ones here could be perceived as very mild scalp irritation - look through the eyes of someone who doesn't believe you to see how the photos could be seen! Maybe show some skin in the photo which isn't hurt (hand/arm/ fingers?), to show the colour difference so people can definitely see it's not just a bad light etc.
If she's just a one-woman band,she won't have much money if you're looking for compensation. Unless she's insured of course, but even so, they won't pay out big bucks.
I'd think about what you want out of this - immediately you need some repair to the skin damage she's done (so, gp best for that?), and also what to do about washing your hair whilst the scalp is healing... I'd suspect any normal shampoo / conditioner will sting a lot at the mo.
Then maybe some scarves / large head bands to cover the scalp damage if it's really visible to other people?
Then another, better, hair salon to give advice on styling/ hair treatments etc, to repair your colour and hair condition. They might be able to advise you even before your scalp has calmed down, and then you have a plan and perhaps a time line so you know you won't be stuck that way forever! You'll also get an idea of costs too, at the better salon/ hairdresser.
Then hopefully you'll be back to normal. Phew!
I'd cost out exactly how much that all costs, plus bus fares, and use that as your lowest figure needed. As all of that are the bare essentials that you are doing specifically to mitigate the damage she has caused.
I wouldn't do anything like posting on her fb as she'll just delete it anyway.
Leaving you toner was ridiculous by the way!