Wondering if I should be on bed rest at this point.
With my last pregnancy I did have a situation where I felt crowded and breathless. I used taurine to help me feel better along with a sodium citrate drink.
1 quart sodium citrate (cheap to make) is made by combining
1/2 teaspoon citric acid (2 grams)
1/2 aluminum free baking soda
1 quart water + 1/3 cup magnesium bicarbonate
Magnesium bicarbonate is made by using 1 teaspoon magnesium oxide shaken in 1 quart sparkling water. (also very cheap)
You can also make that drink half strength.
It does a number of things. The biggest is that it corrects the air hunger, faintness and reduced salt levels in the blood, also correcting acidosis. I started taking it halfway through the pregnancy. I had the best postpartum time yet, too. I could really tell the difference whenever I stopped taking it.
What you describe is how I feel when I am running anemic. My blood test will show everything in the low-but-normal range, but my symptoms disappear when I start taking floradix iron for a few days. Chlorophyl also helps.
At first I thought it was just my petite frame having to deal with growing baby and not much room for anything else (like breathing), but upping my iron levels made a huge difference. I couldn't climb the stairs without loosing my breath and having my heart race (feeling like it's in my throat). All that went away with increased iron levels.
It has to do with the blood levels of acid. (which can be thrown off a number of ways and treated a number of ways) The body will do anything to stay level, including forcing extra respirations or pushing acid into the stomach making nausea, heartburn or the runs. Like a climber going up a mountain might deal with if he has altitude sickness. You might start feeling water intoxicated and sodium citrate lowers the acidity, balances fluids and allows the body to feel better, preventing headaches and the like.