You have identified some food you're reacting to and avoiding them, well done - listening to your body is the key.
Whenever you have pain in your intestines drink marshmallow root tea- it is NOT normal to have an inflammation there. Deal with it as soon as it occurs.
Antibiotics ???? Well I hope you do know many people here are here BECAUSE they took Antibiotics but hey what do you expect from Western medicine?
I see no problem in getting a colonoscopy ... but I doubt you will learn anything from that test.
Your symptoms and my suggestions:
constipation: magnesium supplement - more fiber - more raw veggies
diarrhea: identify what you have eaten before and avoid that food for a while
dehydration: diarrhea will cause it - drink plenty - taking the habit of eating a soup as a meal once a day might be a good idea
blurred vision: vitamin E supplement
eye aches: it might be a symptom of candida - then the candida diet and the entire protocol would be the right thing to do
white stuff on my tongue: it might be a symptom of candida - then the candida diet and the entire protocol would be the right thing to do
muscle spasms: magnesium supplement
moderate depression: vitamin B complex supplement.