You may very well have a parasitic condition. Getting the right doctor is a bitch, must be specialized in "tropical" medicine. My daughter had the super-foul odors, anal probs, itching, etc.
Go to the cdc.gov website, search parasites, get educated then bring copies to doctors to get some real help. It's a horrible thing when doctors aren't educated enough. Many, many people have undergone surgeries, medications, invasive testing, etc. when doctors should be checking us first for these types of infections because they are extremely common and wreak absolute havoc in our systems, blood & organs included for some. That crawling feeling could be roundworms or Tapeworms
(more likely w/"crawling" or wiggling sensation). Anal itching is super common w/pinworms. You could have more than one type. Just get to the right person, but have your data with you. Doctors love to think they've got all the answers right then & there. I pray that your gallbladder surgery wasn't performed unnecessarily. Let me know how it all turns out... good luck!