Thank you for rescuing these bunnies. Are you absolutely sure that they are both female? If these rabbits are around 4 months old, they are coming into sexual maturity and will be able to reproduce soon. It’s happened many times that someone had an “oops” litter when rabbits were incorrectly sexed. It would be good if you could try to examine them yourself, maybe with someone helping you. At 4 months of age, you will probably see a male’s testicles. They look like pink kidney beans. If you don’t feel confident looking at them yourself, you can take them to a vet to be sexed. I checked a couple of state by state vet lists, and there aren’t any rabbit savvy vets listed for Springfield, MO. There are listings for 2 other MO cities, Kansas City and St. Louis, if those aren’t too far away. http://rabbit.org/vet-listings/ That doesn’t mean that there aren’t any for Springfield though. Maybe someone here will respond to your thread and know of a good vet in your area. Otherwise, you can start calling any vets that are in your area and find out how well versed they are in rabbit care. Here is an article that advises how to find a good rabbit vet:
http://rabbit.org/faq-how-to-find-a-good-rabbit-vet/.
Even if the rabbits are both female, when they reach sexual maturity, they can fight if they aren’t spayed, so it would be a good idea to have a second cage if you need it.
It can take a while for rabbits to trust people when they haven’t been treated right in the past, or have been left alone and don’t really know how to interact with humans. Keep sitting with them, either when they are in the cage or out exploring. Speak softly, try not to make any sudden moves toward them, and let them know that you aren’t a threat. Have some greens or a small piece of fruit to give them (if they are used to food like that) to offer them as you sit near them.
Since you aren’t seeing any nasal or eye discharge, the sneezing could be due to some allergy or something in their environment that is bothering them, but it would still be a good idea for a vet to check them out.