Straining with constipation after a C-section commonly causes small tears or piles that bleed a little, which is likely what's happening to you. Using a laxative on your own for two weeks without your doctor's input isn't something to continue.
Next Steps
Please see your doctor now so they can check this and guide you on what's safe to take at 5 weeks postpartum.
Health Tips
Any ongoing bleeding after passing stool needs an in-person look to rule out a fissure that needs proper care.