Sciatica or clot? Crampy calf occasional pain in arch and down from hip. No redness swelling tenderness to touch. Walking doesn't worsen after longtrip

Generally you can't. Unless you have a fever or swollen limb which may suggest a clot more than sciatica otherwise not very specific. I would suggest ruling out the clot first and then workup the sciatica issue afterwards.
Likely scaitica . If there were only two choices, sciatica would be it. This could certainly be sciatica or radicular pain.