The symptoms you are describing are characteristic of "ulnar nerve entrapment" and warrant further investigation. This nerve usually gets compressed at the level of the elbow (but it can also occur in the wrist area) and causes 4rth and 5th digit numbness/weakness just as you mentioned. Of the medications you are taking, the one that can play a role is the Simvastatin which can cause muscle inflammation which then compresses the nerve. Also, Lisinopril could indirectly cause such symptoms by causing electrolyte abnormalities. I recommend you seek medical attention promptly to have the following blood work done: Complete blood count, chemistry panel, blood sugar level, CPK and urinalysis.
Thank you for the positive feedback! I really appreciate it.
I don't think you should wait to see your primary care physician in a few days since if you do have significant muscle swelling compressing the nerves (which I think is quite probable), then a delay in treatment may cause permanent damage or even systemic damage to the kidneys and heart. Therefore I recommend you go to an urgent care center or ER to have this bloodwork done promptly.