Do we change everything now or after treatment? Sorry for silly questions, in a bit of a flap with this
1) Get rid of any infected hay unless you know that the hay mites have come with a new piggy in order to remove the source of any new hay mites.
2) Give all your piggies - including your short-haired ones - a good old haircut right down to the skin in order to remove as many eggcases fixed expecially to the underlayers of the coat is your first treatment job.
An Illustrated Guide to Hair Cutting
This means that you remove as many future mites as possible mechanically that you then don't have to treat cheminally and you really cut down on the outbreak in one fell swoop. Never underestimate the effectiveness of removing as many of your enemies from the battlefield before you start waging your battle! Wash your hands well before and after dealing with guinea pigs or any pets - good hygiene is the same basic principle for transferring germs.
It is unsightly and you may need to keep your piggies warmer than usual (half-heated snugglesafes and bath mats or fleece blankets to crawl underneath; just create a little entrance) but it means that you will have much less of chemical and hygiene battle on your hands for the coming weeks and the piggies will feel a lot less irritated immediately.
You can use a very thin layer or coconut oil or whatever your vet recommends for the very dry skin of your badly affected girl to really get to all the uncomfortable places which are now much easier to see and reach for you.
This is NOT recommended for mange mites.
3) Start any topical treatment immediately after the haircut and once any coconut oil has been absorbed into the skin. It takes about 2 days to be fully absorbed into skin and body. Do the full three rounds at the product specific intervals.
4) Do the deep clean once your F10 arrives and do time your further cage cleans/deep cleans ideally for 2 days after any medical treatment in order to remove any dead and dying mites with the next deep clean.
5) If you are very pushed for time, do a deep clean 2 days after your first medical treatment or as soon as your F10 arrives and then again 2 days after your last round of medical treatment. In between, you just clean/change bedding as normal.
I hope that I have been as clear and as precise as you need?