Foundation water seepage?
If diverting the rainwater away from the house doe not stop this problem, potentially the problem is caused by the fluctuation of the groundwater, or there is a spring near that corner of the house, provides the basement wall wasn't adequately waterproofed. Unless you don't mind wasting your money by trying some fixes, the proper way is to involve a Civil Engineer to pinpoint the source of the problem and find a feasible, yet durable and economical solution.
As a homeowner myself, I might be tempted to grout the block wall solid, wait and see before resort to hiring an engineer. Also, you shall keep the basement well ventilated. Good luck.