Have they done an ultra sound of your ovaries? I would start there, if all the other tests have been normal!.....keep me posted
There is some good information above, but I would just like to add that many over the counter medications can contain lactose or gluten so you need to be extra careful, especially if you have any food allergy.
It could be you have more than one issue going. For example, your profile says you are a young woman, likely one who is still menstruating.
People can get bloated during their menstrual cycle and also get headaches (which at times in itself can bring on nausea) from normal hormonal fluctuation (for example, a dip in estrogen when the mense begins). Menstrual related hormones can also cause nausea (both a sister and I have experienced this). Endometriosis can cause abdominal pain and cramping related to the mense and sometimes, endometrial implants can be found on the bowels and then grow into them.
It is not at all uncommon for the menstruating female to become iron defecient. Symptoms can start to exhibit themselves (I had some myself at this stage) prior to your complete blood count showing any number outside normal range.
You may want to ask the doctor specifically for testing of your ferritin (iron stores) and iron saturation percentage levels. Some symptoms of iron deficiency are (see private message for more info):
constipation, headaches, hair loss, itching, fatigue, impairment in cognitive function
While hot liquid may help move your bowels, caffeine is actually a constipator, so I hope you've stuck with decaffeinated coffee.
Have you been tested for a gluten allergy, or just experimented with elimination? Cheese is a constipator, and if you have a lactose intolerance, that can upset your bowels. You may want to ask the gastrointestinal specialist, if any pain is in your upper right quadrant about a HIDA scan of the gallbladder or an MRCP to look at your bile duct work, in case the CT scan missed something.
To reiterate what a previous poster brought up, getting thyroid function checked again would not be a bad idea. For more thorough testing, you may want to ask if you could have free T3 and T4 levels tested as well as thyroid stimulating hormone (TSH).
Regarding the dairy products, have you made the switch to lactaid milk to see if that was helpful? Have you tried rice milk? This is what I drink (vanilla rice dream), because milk gives me bad acid reflux, and soy milk gives me headache, plus I have interstitial cystitis.
Despite your hormone profile, the clinical features fit in with hypothyroid status.Perhaps you need a review.
Best wishes.