Brief Answer:
Various causes; you need to report to a doctor at the earliest

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. The lymph system helps with the transport of lymphatic fluid through the body. Any blockage or damage to the lymph system can result in retention of fluid in soft tissue which can in turn result in the swelling, which can again at times be restricted to one side as well. To confirm or rule this out I would recommend a CAT scan which would be elaborate but specific.

I would also recommend the following:

+STD-panel (especially including herpes zoster, which can manifest with some serious neurological symptoms that can match those you are experiencing)
+Comprehensive blood panel to check for infections (especially viral ones)
+Kidney function and blood pressure: To see if the fluid retention can be due to abnormalities in the kidney
+Medications
+Heart abnormalities (e.g. congestive heart failure)
and a few other conditions.

Needless to say ma'am, your presentation requires medical attention at the earliest and I would thus urge you to visit your doctor at your earliest convenience. Please also feel free to write back to me for any further clarifications, I am always here to help.

Best wishes.

---