There are many potential causes of "foot drop" The fact that it is occuring on just the left, suggests possible nerve entrapment. Nerves can be entraped at different locations, if you have a history of back pain and sciatic, this should be considered. There are other explanations for foot drop such as neuropathy (genetic disorders, or diabetic). If there is a medical history related to possible perpherial neuropathy start with your primary care physician. Stretching exercises is NOT the answer for foot drop. It is unlikely that additional strengthening exercises is the answer.
Damien Howell PT, DPT, OCS
www.damienhowellpt.com