Can a disc bulge (not herniated) cause temporary sciatica throughout the day eg muscle twitches sharp leg pain then go for a few hours or days?

Not typically: most disc bulges do not touch nerves to cause any nerve related symptoms. At times Radiology reports may call something a broad based disc bulge, where there maybe other things going on as well including decrease in disc height, etc. that in combination can push on a nerve and cause symptoms down the legs. Seek care from a Spine Specialist.