Hair Loss treating for possible mites with Ivermectin - need help

Hi everyone,

One of my 6 guinea pigs has been experiencing hair loss, so I have decided to go ahead and treat her for mites using ivermectin. I just had a couple questions:

1. This is the ivermectin I have purchased from Amazon: https://www.amazon.com/gp/product/B00JAL3AAW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1#.
It states that it is a pour-on product that contains 5mg/mL Ivermectin, so I am planning on using this dosing info from Guinea Lynx: https://www.guinealynx.info/topical_ivermectin_pour-on.html.
I was wondering if someone could just verify that I am purchasing the proper product which corresponds to that Guinea Lynx chart. I know I am probably being obsessive but, as you can imagine, I would never want to hurt my piggy and just want to make sure I'm not missing anything.

Also, has anyone else used a similar pour-on Ivermectin? What was your experience like?

2. Will it cause the pig pain to put the ivermectin directly on her bald patches? I know you are supposed to apply it on the neck behind the ears, but unfortunately that's where she has lost most of the hair.

3. Should I treat her cagemates even if they are not showing symptoms?

Thanks guys! I really appreciate any help you can provide!