Hi!
I would recommend to see a vet for potential ringworm tomorrow during normal opening hours; it is not an emergency. Please do not put anything on the patch as it is like wiping a crime scene - unless you really want to hear your vet cursing from as far away as the car park for making their job a lot more difficult. It is much better to get going with the appropriate good quality stuff when you know what you are dealing with.
Here is our ringworm information; it is VERY comprehensive, practical and step-by-step. Key is absolute hygiene or you won't get rid of the long lived invisible spores and will end up with a long running saga of recurring outbreaks. In nearly 15 years of existence we have had ample time to find out what is effective and what not and in just how many ways ringworm spores can be passed on - and what you can do to avoid this from happening. Your best friend will be a vet grade disinfectant like F10, which is widely available online.
New guinea pigs: Sexing, vet checks&customer rights, URI, ringworm and parasites
Ringworm: Hygiene And Pictures
PS: I would strongly recommend to not feed the stuff you are holding under your piggies' noses. Neither peas or carrots should be fed regularly; it is like feeding humans on chocolate and won't help them stay healthy and live longer. There are much better treats if you really feel like treating and not rather concentrate on turning feeding time into active enrichment time instead.
Long Term Balanced General And Special Needs Guinea Pig Diets (see chapter on treats)
Enrichment Ideas for Guinea Pigs