Medication

Question
I have two female guinea pigs, that I know have either mites, or lice. The mother I believe has had them since I got her, and as I was learning more about guinea pigs I realized both her and her daughter have many of the symptoms of mites and lice. Although I am not sure which one. I would like to avoid a vet exam if possible. While looking for information online, I found a medication called invermectin that the vet here offers(I would get them this if I knew it would work). I was just wondering (we don't have any small animal vets here, and the dog and cat ones don't know much at all about guinea pigs) if invermectin would kill both mites and lice? I know that I would have to get two to three shots for each guinea pig, about 7-10 days apart. One veterinarian reccemended over the phone, frontline flea and tick spray for cats and dogs would also get rid of lice and mites, but I am a little hesitant to 1. use dog and cat spray, and 2. use something not made for these specific parasites. What is your opinion about getting them both invermectin shot(s), and/or the flea and tick spray?
 Thanks in advance for you help, and all the previous help you've done for me!

Answer
Hi Adria

you can try Neem oil which should help.It needs to be a  dilution rate of four parts of carrier oil to one part of Neem oil.
Rub the oil in and leave it on for a couple of days then shampoo it off. Leave a break for about five days then repeat the procedure and see if it makes a difference.
You can use Prioderm shampoo of you cant get Neem oil, its just as good. It is the stuff used to treat kids head lice and its safe for guinea pigs plus its way cheaper than anything the vet will give you.
You might have to let the vet give them a shot of Ivomectin or similar but we will deal with that if this remedy does not clear it up :)