IBS with tenesmus every day

I have tenesmus everyday that drs say is IBS. I don’t have flare tops. I have this every day along with flatulence. 3.5yrs now. All kinds of tests and everything negative. I am 64yr old male and this came in suddenly 1 morning with 2 short loose BMs. Sensation then never went away. My BMs seem normal every morning, but the it feels like I haven’t gone!
Any advice or help appreciated! Have tried peppermint oil, Bentyl,Amitriptyline, etc. No help. Diet does not matter. Help! Thanks