Frequent Urination. Urge of urination?

Hello Doctor I am 31 years old, I have been facing problem of frequent urination from last 15-20 days. I have consulted Doctor then he said that it can be due to Diabetes or UTI or urine stone. Sugar level is normal and don't have any kind of pain or burning sensation while urinating. I took medicine on UTI  prescribed by doctor for 5 days however I  still feel urge to urinate frequently. After urinating I don't feel satisfied and always feel that some urine is still there inside penis particularly at the end of penis (from inside) I masturbate only once in a week and never do harshly or by applying much force. I feel that it started when I masturbated twice in a day. (I already did twice in a day  few times in past but never faced any problem) I tried to decrease intake of water for few days still it didnt work Am I having this problem because of masturbation? What can be reason and solution on frequent urge of urination? Please suggest Thanks in Advance