You are 20/M c/o frequency of micturition for the last 1 wk. after passing urine you feel as though some urine is left behind in the bladder. You say that this problem is more if you don't eat well or drink enough water.
Even though you have not mentioned burning urine, this is common with Urinary Tract Infection
Moreover you clearly say that if you don't drink enough water you have this problem. The problem may be anywhere in the urinary tract
but common in CYSTITIS
(inflammation of Bladder)
Investigations and Treatment:
Whatever may be the cause - Take plenty of water + urine alkaliser + mild diuretics.
1) a complete urine analysis including culture sensitivity - treat accordingly
2) if the above reports are normal, you need a cystoscope + USG + micturiting cysto urethrogram
( not all - but only step by step)
Consult a urologist
- Treat if there is any problem. You will be totally alright