Yes I am familiar with these diseases, and they can be together. The fact that you were diagnosed with collagenous colitis is interesting, and you can get "flares" of this disease requiring to use prescription medications for this disease (usually steroids, such as budesonide). Other medications include mesalamines, also requires prescription. I don't know if you have tried those already, but you should definitely visit a gastroenterologist for further evaluation.
There is also the possibility that you developed an infectious diarrhea, and this needs always to be ruled out (such as parasites, Clostridium difficile, other bacterias, etc).
If your symptoms are so bad as you describe, you may even need a repeat colonoscopy with biopsies of your colon to make sure nothing else is going on. While you get to your doctor you can try over the counter imodium, but this usually is not enough.
One last thing: sometimes issues with the upper gastrointestinal tract are the problem (duodenal problem causing malabsorption such as celiac sprue, lymphoma or infection) but these causes are rare, but it may not be unreasonable to do an upper endoscopy with duodenal biopsies. Again this needs to be discussed with your gastroenterologist.
Hope that helped, let me know if you have any further questions.

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You are welcome! hope you get better soon

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