Brief Answer:
Cause cannot be exactly determined, but feel it is not related to the lungs

Detailed Answer:
Hello ma'am and welcome.

Thank you for writing to us.

I have gone through your query with diligence and would like you to know that I am here to help. Actually, quite honestly I cannot accurately answer that question without going about a number of investigations to find the exact cause. But from my experience, some of the most common causes for leg pain along with numbness are the following:

+Nerve distress: Most commonly the sciatic nerve
+Lower back problems: Either due to some underlying condition (e.g. slip disc, herniated disc, etc.) or a recent injury
+Arthritis
+Electrolyte imbalance
+Arthritis
+Peripheral neuropathy (e.g. caused due to diabetes)
+Lung abnormalities that result in circulatory abnormalities (like you have, but less likely in my opinion).

I would recommend a visit to your doctor for further evaluation and management accordingly. Please also feel free to write back to me for any further clarifications, I am always here to help.

Best wishes.

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