For the constipation try taking magnesium (citrate or chelate) 250-1000mg per meal time until bowels are more frequent. Flax seed although does help bowel movements it is supposed to help bulk up bowel movements.
dizziness could very likely be vitamin deficiency in which case I would recommend seeing a natual doctor like a naturopath or whatever you chose.
Food has a lot to do with all your symptoms so read up on IBS foods, stay away from fatty foods, dairy products (except yogurt), coffee, alcohol, sugars, until you get things under a more manageable state.
Also check the PH levels of your urine by using PH home test strips (purchased at a helath food store) and/or try using digestive enzymes. Avoid drinking liquids during meals and eat as many vegetables as posible as these are almost the only non acidic foods (alkaline foods).
Good Luck
Have you went to a gastroentologist? If not for sure try to see one.
also perhaps ask your family doctor to refer you to a doctor for anxiety.
Could be signs f IBS. Your gastroenronologist can help decide that.
For now stay away from spicy foods, oils, dairy, caffine, and sugars.
If you would like to know what i eat let me know,, however this may not be good for everyone.
Good Luck!
Snooze