Brief Answer:
as explained in details.

Detailed Answer:
Hi.
Thanks for your query about your Mother.
To recapitulate: Female/74 - cervical cancer 30 years ago - lymphedema in one leg since then - treated in ER 5 week ago for constant severe pain in groin - leg hurting constantly - sore - hard to use sleeve on it now - arthritis and missing disc n lower back - wants to know the cause of pain ...

My thoughts:
Since the treatment of cervical cancer 30 years ago and lymphedema since then indicate that the cause of lymphedema was related to the lymph node removal or irradiation but still sufficient not to cause more edema.
The pain in groin could have been due to inflammation of the inguinal lymph node causing the blockage of the precarious lymph channels and thus increasing the edema and the pain.
The missing disc can also cause radiculopathy pain, added on by arthritis.

I would advise you the following:
Please post the reports of the tests done so far.
Ultrasound with color doppler of the whole limb, inguinal area tracing upwards till the diaphragm for all the lymph nodes.
I hope that the patient has been given proper antibiotics and anti-inflammatory medicines.
Elevate the affected limb above the heart level in laying down position to facilitate emptying of the lower limb edema by gravity.
Test of blood and urine.
MRI of the lower spine to see if the pain can be related to the missing disc or such problems.

I hope this answers your queries and helps your Mother further.
Please feel to give feedback and ask for further relevant queries if ou feel that there is a gap of communication.

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Brief Answer:
Myelography be done when MRI is not possible.

Detailed Answer:
Thanks for your feedback.
In such a case where MRI is not possible, CT or X-ray myelography can give idea about cord compression. Please get this done along with other investigations as advised above to get the proper diagnosis.

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