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 tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.
Episodic weakness or sensation of weakness, which completely resolves, can be seen in a few neurological conditions, including Transient ischemic attacks ( TIA) ( or "mini strokes") , seizures and rarely with migraine headaches. These are sometimes very difficult to diagnose as by the time one seeks medical attention, the symptoms have already resolved. I am not aware of your past medical history, however if you have risk factors like high blood pressure, diabetes, heart disease, history of smoking or alcohol use, you could be at risk of TIAs. Similarly if you have a history of headaches, or have headaches with these symptoms of weakness, you should be evaluated for a possible diagnosis of complicated migraine. Seizures rarely may present with out the classic "jerking" symptoms, and may just result in transient heaviness.
I would suggest that you see a neurologist for a full neurological assessment, soon. Where these symptoms may not mean anything, it is best to rule out serious neurological conditions. Here I have described a few differentials, but strongly feel that a formal neurological assessment is warranted.
I hope this answers your questions. Thank you for using this forum