Chronic gas, help please!

I am a 23 year old female, who has been suffering for 2 and a half years with terrible gas. It began with an aggressive sequence of antibiotics for tonsillitis. The gas is far worse in the evening, with or without eating dinner. In the last 6 months I have added another symptom of Levator Ani Syndrome (chronic muscle pain/spasms in rectum/pelvic floor), probably from trying to hold in gas so frequently.

I have seen several GI doctors and tried a variety of treatments, both pharmaceutical and OTC ideas as seen on this site. I have tried many different probiotics, since my first thoughts were that it was gut flora-related from antibiotics (Florastor, Align, VSL3 double strength, Digestive Advantage Gas Defense, LP299v, kombucha, kefir, yogurt). I got the hydrogen breath test for SIBO; results slightly +, took Xifaxin, tested again, negative, but didn't change symptoms. Negative breath tests for fructose malabsorption. Tried levsin, nortriptyline, Iberogast, aloe vera juice, L-glutamine, Mikes hypnotherapy tapes. Digestive enzymes may help slightly.
I have had colonoscopies, endoscopies, ultrasounds, stool tests - all normal enough (besides a peptic ulcer, which as since healed).
Diets: 3 months no gluten, allergy elimination diet, low FODMAPs (worked for ~a week)

I eat healthy, don't drink soda, avoid all potential notorious gas-causing foods.

I'm currently taking Librax 3x/day half hour before meals, and this definitely helps during the day, which is an improvement, but the chronic nightly gas is unrelenting.
I recently started CBT and started Cymbalta 30mg (for the Levator Ani Syndrome pain and also depression).

This has completely ruined my social life and mood. Does anyone have any suggestions of things I could try, either pharmaceutical or life style-wise?

Thanks.

Unfortunately haven't found a solution. I'm scheduled to get the SmartPill test this December-- hopefully that will show some motility problem, which is what my GI doc thinks it is. For the time being I've just been super restrictive in my diet, rice + meat sort of thing.
I'm usually able to hold in the gas when I'm in social situations (hence the levator ani syndromes, I think)

Hey, IBS could be caused by a candida infection. I had embarrassing uncontrollable flatulence like you for a whole year and even going on the fodmaps diet didn't reduce it. The kind of flatulence was very frequent and even when eating foods that were fodmaps safe or typically healthier foods like veggies, fruit, wholegrain, meat, rice. Everything gave me flatulence, i felt it was ridiculous. It took me a year to discover it was candida in my intestines. Candida has a broad list of symptoms you should check out and you may have other forms of it like a vaginal yeast infection. I didn't notice but during the year that i had candida infection i was lethargic, more anxious, depressed, moody, unfocused and foggy-brained. I started a strict candida diet last week - eggs, meat, fish, low starch vegs, almonds, avocado, no fruit, sugar or wheat rye barley polenta oats buckwheat rice anything starchy and took antifungals coconut oil and pau d'arco tea at the same time. After 5 horrible days of die off symptoms yeast was visible in my stool and i felt relieved that my candida was real. Probiotics are also a must to fight the candida as well as rebalance the gut flora which is key to recovering from ibs. A good one i've found after tiring research is Jarrow Dophilus. I have IBS-C and probiotics will definitely help with regularity preventing any breeding ground for the candida. The strict diet should be continued for a few weeks to a couple months and after that maintain a diet that allows only restricted amounts of sugar and lower carb grains like buckwheat quinoa brown rice and other lower sugar vegs/fruit/nuts. All sugar - fructose, dextrose, lactose and more- feed candida so be careful of anything and check labels . It's a hard process but I'm already feeling better after a week and i see light at the end of the tunnel.

Also many yeast infections start from taking antibiotics which kill the good bacteria needed for good digestion. Yeast is normal but not when its overgrown. Poor digestion leads to the frequent gas.