What Causes Skin Flare Ups And Hair Loss?

I have been having skin flare ups- rosacea, burning, flaking. Also, scalp buring and hair loss. The scalp buring and hair loss has improved but my face has not. I have always had stomach issues and have concerns. My stools sometines smell like chlorine and sometines have muscus. All gluten/celiac testing is negative . Could this be an immune or malasorption issue. I am now taking vitamin B and D with hopes to boost immune. Doctors keep testing. Any thoughts?