Here are a few possibilities; involvement of nerve endings in surgical incisions
can cause such stabbing or piercing pain as the nerves begin to heal; urethritis
can cause sharp pain
as urine is passed along the inflamed urethral surface; possibility of some left over adhesions. You can increase the intake of fluids and take the urinary anti-spasmodic, Flavoxate. Avoid excess strain and take as much rest as possible until symptoms subside. You may also get urinalysis
and sonogram of the pelvis done. Hope this helps.