should i fire my oncologist?

mom has had stage 4 for the past 2+ years. we've been with her present onco for a little over a year. she was on avastin/5fu/leucoverin but stopped responding to it, so onco put her on erbitux recently. some things have pissed me off about this though and would like some incite from other members as to what you would do, feel free to correct any of my assumptions below.... mom developed the classic erbitux acne. at first her onco said to go to a dermatoligist, but when i told her that acne is a common side-effect (i have been doing alot of my own research on erbitux), she says, 'oh yeah'. that seemed questionable to me. i inquired about prescribing her an antibiotic, she said not yet, shed rather save the stronger medicine in case she will need it in the future (people develop an immunity to strong antibiotics over time), so she told her to take some neosporin and benadryl. and if that doesnt work she'll think about putting her on something stronger. its helped some, the acne has gone away, but she still has redness around her nose. shouldnt the onco have prescribed an antihistamine or antibiotic BEFORE she started erbitux? from what ive read if you take them AFTER you start erbitux, its not as effective in getting rid of the acne/rash. when asked if she checked with her surgeon if my mom has a KRAS gene mutation, she said no. what?!?!  its my understanding that erbitux WONT work if patient has a gene mutation. (ive also read on other places that it might not matter....so i not sure what to beloeve now)  dunno if the onco is just throwing chemo drugs on the perverbial wall, hoping something sticks. lastly, she said that if a patient develops the acne, its a sign that erbitux is working. ive read that developing acne IS NOT an indication at all of whether erbitux is working. so am i just thinking that im smarter than my moms onco, or should i put faith in the docs expertise? im pretty stuck since my parents dont speak english very well, so their choice in doctors is limited. ive been taking care of this for over 2 years and its been a rollercoaster, and i might not be able to tend to things like i have been for very much longer  (might get a new job that will require more of my time) what would u do? any advice would be appreciated. thanks very much