Digestive problem. An abrasive process!

I am 29, from India, usually kept vegitarian diet, past diagnosed with constipation 6 years ago, also history of anal fissure and mild hammeroids. But from past few days I have been noticing a slight change in my bowel habit and frequency I went to multiple doctors, they all said ibs, I followed some instagram tips taken some sodium bicarbonate and that day I felt mucus with one drop of blood as well, then also I consulted multiple doctors they all telling ibs. Right now no other symptoms but felt like passing poop and then air passes and like two times per day is the frequency no blood no cramps no other symptoms, but I kept worrying. I went for USG and it came normal. Please suggest I should go for colonoscopy, as doctors tell it as an abrasive process!!!