Fluttering sensation in left side

Hi, I’ve been having a weird fluttering sensation in my left side on and off for 3 months, I’ve also had a dull ache on back passage again on and off, GP thinks IBS, I do have piles, she has examined me and happy nothing sinister, I also had a colonoscopy 2 years ago where a small non cancerous polyp was removed, she said she does feel the need to explore further and says it’s IBS, I do suffer with health anxiety and just wondered if my anxiety could be causing these fluttering sensations? And if anyone else has experienced the same? They’re not painful in any way