This is fairly common. Someone in the car group will have a bad headache and still go out in field circus. I have been in car groups where one or more people have a bad headache (usually from not getting enough sleep or from the pxxx poor Pioneer Diet). Usually, they will take a couple of aspirin or Tylenol and keep going in field circus.
I have also seen people in field circus with a cold or the flu. They will usually take cold pills and keep going as long as possible with their condition. They almost never quit early. I can remember when I had a sore throat, they kept me out in field circus as long as they normally did. I have also been out once with a flu (it was going through the congregation, probably the result of the a$$embly), and it was hot. They wanted me to stay out all day that day, too.
Standard procedure for these conditions is to stay out as if you were not sick. What happened was that they would treat the symptoms. I have seen people taking different cold preparations just so they could make their quotas in field circus. What they didn't allow for is that householders do not want to catch a cold or the flu because of a cult wanting its members out no matter what. And, when I had a cold (sniffles bad enough to be blatantly obvious to the householder) and used that as the excuse, Brother Hounder had a hard time accepting that excuse.
I have heard of people out with other conditions. The most common is back problems. Getting in and out of the car quickly, as is expected in field circus, is actually harder on one's back than lifting heavy loads with your back (I know; I have had back episodes that were aggravated by field circus but not by lifting with my back). People are supposed to take pain pills like Doans or ibuprofen, and ignore the pain. Of course, that is not safe since it can result in more damage to the muscles. Pain is supposed to be a warning that you are going too far, and I do not recommend taking pain pills except to allow you to sleep or to bring the pain down to a bearable level while still serving its purpose.
Many other conditions can affect performance in field misery. Depression is blatantly obvious, since you are supposed to project joy and cannot if you are depressed. Usually, they make you just pretend while holding you to all the normal rules. Hand injuries (usually acquired while repetitively handling litter-ature) mean difficulty in handling the litter-ature and the Bible. I have also seen people out with arthritis that affects their ability to walk up stairs, and they still have to go out and climb stairs. To these people, a flight of 6 or 7 steps is like climbing a mountain because of the pain in their feet.
Of course, they don't care. So often you hear of the pioneer in the iron lung that you are shamed into going mountain climbing with arthritis in your foot. Or, they shame you into going out with a severe headache because of the "brother" with Marfan's syndrome that is able to pioneer. I have seen the excuse of tuberculosis and AIDS patients going out in field circus being used to shame a person with a bad cold or the flu into going out. People with toothaches, backaches, and leg- and handaches are also shamed by those stories of people going out all the time with all sorts of painful diseases and handicaps.
Not that it's necessary to go out with a cold. First, going out exposes one to catching a cold in the first place. Then, the Pioneer Diet is wretched for colds: most of them are tired and rely on coffee along with their cold pills to go out when they have a cold. I just found out that being tired is not a primary symptom of a cold: if you are already borderline deficient in energy and you catch a cold, you will feel sluggish and cold (plus it will take needlessly long to get rid of it: a cold in an otherwise healthy person is a weeklong nuisance that can be messy but otherwise will not slow one down). However, if you are affected with fatigue when you catch a cold, there is no reason in the world why you should have to waste even more energy going out in field circus. It will make it last longer, expose you to complications, and make you feel even worse. Plus, it will expose householders to your cold needlessly.