8 mm calculus has about 20-30 percent chance of spontaneous passage from ureter with in 3 weeks If it does not come out endoscopic lithotripsy(surgery without incision)is advisable as potentially damaging the affected kidney. Consult a urologist in locality for exact medical treatment. General guidelines are Plenty of fluids,adequate rest, Potassium magnesium citrate mixture 15 ml mixed with glass of water thrice daily, Antispasmodics for sympotamatic pain relief. Associated infection may require appropriate antibiotic, Adding weak diuretic&alpha blocked may also help