The pain began as lower back pain and suddenly became sciatica. foot and calf have numbness. im seeing pt. how concerning is the numbness?

Not very: With 'sciatica' there is pressure on a nerve with symptoms felt in the distribution of that nerve somewhere in the leg. Numbness, tingling and pain are common and usually resolve with treatment over time and there isn't much fear of permanent problems. Weakness is also seen and if not treated urgently can lead to permanent functional deficits and should be monitored closely and treated ASAP.