Pain when passing stool five weeks after delivery usually means the fissure hasn't fully healed, and it flaring back up right after you stopped Looz fits that pattern. Continuing a stool softener like this a while longer is reasonable for postpartum constipation, it isn't something that causes harm with extended use.
Next Steps
Keep up the fibre and fluids you're already doing, a warm sitz bath after each stool eases fissure pain and speeds healing.
Calcium tablets are fine alongside this and won't worsen constipation as long as you keep your fibre and water intake up.
Health Tips
See your gynaecologist or a physician if the fissure isn't healing within two weeks or the bleeding increases.