1997 Mazda MX6 Clutch to floor.

Recently I noticed my clutch pedal would not come up more than halfway when depressed. The car has a combination reservoir for the brake and clutch masters and the brakes were recently bled. The fluid is full in the clutch part of the reservoir and I can't detect any leaks anywhere in the lines. I tried bleeding the clutch from the bleeder on the slave but I keep getting air. Sometimes small bubbles, sometimes huge. I'm certain I've bled it enough that it SHOULD have cleared all the air out but it keeps coming and the pedal is the same as before or worse (used to be hard to shift gears with car running, now impossible. Can shift around ok with car off). Is my problem with the master, slave, clutch internals or? Clutch had never slipped or given any problems before this.

Edit: Am just bleeding with the slave cylinder bleeder screw. Do I need to bleed the master seperately and how?