I assume that your terrain is totally flat living in Illinois. However, try diverting outside water away from foundation is step #1. If you have any slope at all, a french drain will do the trick. MAake sure that your gutters & downspouts work properly. Get out the hose and test them. Make sure they deposite the water a good distance from the house, especially at the wall you are referring to.
Next, depending on what is next to the outside wall (patio, driveway, pool, etc.), If you have access to the outside of the wall, think about digging down and sealing the outside of the foundation. Always try to divert water from the outside first.
I have seen a system where the leaking wall was next to a large exposed aggergate patio & the guy didn't want it dug up. The terrain was flat so they designed a system to drain off the water from the outside. They installed a stone drain bed that lead to a septic-type plastic container with a pump to remove water. This was however an expensive system.
Finally, you can seal the inside of the block wall using a block sealer that contains portland cement. The UGL Drylock is probably the most expensive but seals the best. I used a less expensive block sealer because I did not have serious water problems. Since your foundation is stone not block, you might have to trowel first with a hydraulic cement mixture. I think there are products sold that have good waterproofing qualties. Talk to people who install in-ground pools using cement walls. They should be able to enlighten you about waterproof products.