Talk to Gastroenterologist on Persistent Anal And Bowel Symptoms. Pain, Itching, Gas, And Mucus Discharge

About five years ago, I experienced significant weight loss (from 52 kg to 40 kg) and pain, burning, and itching in the anal, anus during and after bowel movements ( passed the stool). There was also a persistent foul odor.

At that time, I did not receive proper treatment.

Currently, the problem has returned:

Urgency to pass stool immediately after eating

Constant gas, often unnoticed by me i can feel, but noticed by others due to odor

Itching in the anus anal after bowel movements

Occasional small amounts of white discharge

Symptoms worsen during travel or prolonged sitting

Please tell me about this illness, and which important tests I should get done before consulting a doctor so that I can have them ready in advance.