Hi. For about 3 months Ive had phlegm production that is yellow on color. I had a cough for a few weeks, which has gone away now. I get nauseous after eating, with the feeling of pressure on my stomach. I get very light headed if I hold my breath for a few seconds, and I feel all the blood rushing back to my head when I let go of the breath. I have a low-grade fever. Also it takes more energy than normal to breath in deeply. Not sure what is going on. Can you help?

If it were 3 days or even 3 weeks, I might say just flu, but 3 months needs a complete examination by a doctor. It could be anything from easily treatable to serious. If your lungs are full of mucous then of course you are light headed - you aren't getting enough air exchange. Once an hour, while sitting, take about 50 deep breaths but stop if you get dizzy. But see a doctor too!