I use oxygen for COPD and Cluster headaches. Last week I was getting a headache so I laid down with my oxygen (bottle) with the setting on 3. For a full blown headache I am directed to use 8. After about 15 minutes I began getting a different headache, nausea, my heart seemed to speed and even jump a couple times, my abdomen and back were killing me (I have degenerative disease) and I felt like I wasn't getting oxygen. I got up to go throw up and fell, which I have done 3 times prior in a month because my sciatica is bothering me (my Doctor is aware and is ordering an MRI). I don't know if it was the sciatica or something else but it took about 10 minutes before I could get my equilibrium back and walk. Since then I have been ill with stomach problems, diarrhea, tightness in my chest, headaches, chronic fatigue, nausea and bad balance. Many of these things I have had off and on because of my med's but this is different. I talked to a pulmonary person and the American Lung Association because I thought it may have been my oxygen. I was told occasionally you can get a bad bottle or that it's possible to get oxygen toxicity (similar to the bends) but that wasn't likely. Today I looked up the side effects of my Metronidazole Cream and found if it was pill form it could explain almost every symptom. I was only using the cream but about an hour before using the oxygen I applied it to my nose, cheeks, forehead, etc. I use a mask for oxygen, could my problem be from the cream?