Adobe Animal Hospital anyway.
The veterinary assistants stuck the thermometer in their nether regions to obtain a stable reading. There was a lot of pitiful squealing, reminding me of my own doctor's visits. One guinea pig's temperature was 107 degrees F., which an antibiotic and anti-inflammatory treated after a couple of days.
The doctor suggested that we hand-feed both with a liquid formula for a week until they got their appetites back, which we did and they did. The assistants clipped their nails, again to more squealing.
The hospital charged us less than $100, including medications, for each guinea pig, a lot when the price of a new animal is about $20, but much less than the cost of a visit for a dog. (Every vet we've been to scales down their rates for these common small animals.)
Love may have a price, but we're not close to reaching that limit.