Okay, so I've been seeing my dermatologist for about a year and a half and finally got put on accutane. I won't get into it, but Ive caught her messing up and also lying several times. I think she is severely unqualified for her job. I weigh about 60kg, for my first month she put me on 40mg once daily. Its my second month, she sent a 40mg twice daily prescription to the pharmacist. That seems like a lot to me, especially since I told her I've been dealing with bad back and joint pain. (and she said this wasn't even my full dosage??) I'll keep taking it once a day until I'm sure its okay.
Dermatologists write out accutane Rx as a significant chunk of their daily task, so I wouldn't be too worried about if she got the dosing wrong for you. She may have felt like your progress in the last month wasn't as much as she's used to seeing and upped the dose. If it gets better she may likely taper it back down. At 80mg per day you are getting 1.33 mg/kg/day which is less than the maximum of 2 mg/kg/day for severe cases.
I think you'll be fine. Symptomatic treatment of your side effects such as omega 3's, NSAIDs, hot baths, may give you relief.
I am likewise on 40mg per day. I had moderate postular acne and am really happy with the results so far! It depends on whether your acne was mild/moderate/severe. If severe, it's likely you'll be upped to 120mg per day (the maximum dose). Seems like she upped you from 40 to 80mg pretty fast though, in my opinion. Did you get onto her and ask about this? I know derms can seem like gold dust to try to get a hold of at times. D:But I wish you the best!