Consult any expert physician if you are suffering from the drops after urination, and do istibra while urinating ie make it sure that drops have stopped though it takes longer time. Also use tissue paper or clod for istinja so that your clothes are not impure due to the drops. The drops which one experiences after urination do not make ghusl wajib even they are the drops of semen. As ghusl only becomes fardh when the semen discharges with jerk and lust. Hence in the question mentioned above if you are in doubt with regard to semen, madhi and urine then you should not worry, it is lawful for you to offer salah after making istinja on the said pattern, there is no need of ghusl. (Imdad al-Fatawa: 80/1, pub. Maktaba Darul Uloom, Karachi)
Allah knows Best!
Darul Uloom Deoband