Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine you and obtain a history, I can not provide you with a diagnosis. However, I will try to give you some ideas about what some possibilities are.
Regarding the symptoms of numbness you had on the left side of your body associated with vision loss and headache, it is possible that your symptoms were due to migraine. GIven that your MRI has been interpreted as showing no abnormalities, a cause such as tumors or multiple scelrosis is less likely (though I can not completely exclude these since I can not view your MRI as that is not part of our role on this website).
Migraine is a type of headache disorder in which symptoms may or may not include an aura such as visual disturbances or tingling, followed by a headache that is often pounding/pulsating, associated with nausea and sometimes vomitting. Patients will often complain of lights bothering them during the headache. This type of headache is highly treatable should the diagnosis be made.
Regarding the burning symptoms in your leg, it is possible you have a neuropathy. A neuropathy is basically an irritation of some sort to the nerves that supply our skin and muscles with innervation. One type of neuropathy that affects the latera thigh is called meralgia parasthetica. This often occurs in overweight people or those who wear tight pants or following certain surgeries, basically anything that can compress the nerve that supplies innervation to the lateral thigh. This often improves with time and if not is treatable with medicaiton.
Whether or not there is a neuropathy can be determined from history, examination, and tests including one that is abbreviated EMG/NCS. This asseses how well electricity is conducted along nerves and how muscles respond.
Based on your symptoms, it sounds like you would benefit from evaluation by a neurologist. After obtaining a history from you and examining you, he/she will be able to determine whether or not your symptoms are neurologic and may choose to do additional testing.
Thank you for using the forum, I hope you find this information useful, good luck.