I have been taking doxycycline for about 5 days now, 100mg 2x per...

I have been taking doxycycline for about 5 days now, 100mg 2x per day. I was fine the first couple days, but now I am noticing a bit of nausea within an hour after I take the morning dose. It normally goes away after abour one hour. I also noticed that I am rather cloudy in the head during this time, and I can't seem to form coherent thoughts. Of course I noticed this while in the grocery store trying to shop with a 10 month old. NOT A GOOD TIME!! Anywho, I am stuck with this medication since my first course of Biaxin was a failure. Hopefully it will end soon and the pneumonia will go away. So far I feel no better.