Burning after urination along with small blood clots and very little urine coming out each time points toward a urinary tract infection, and unprotected sex can trigger this in women. The small amount passed each time with that urge is a classic UTI pattern rather than something coming from the vagina.
Next Steps
Get a urine routine and culture test done soon, and drink plenty of water through the day. A urine infection usually needs a short course of antibiotics once confirmed.
Health Tips
Please see a gynaecologist soon, and go in urgently if you get fever, back or side pain, or heavier bleeding.