Can NoT breath ~! and IRon deficiency !

Since last night, I have to deep breath for each breath I took and it makes me tired and light headed. I never had this before not even during My swim/run. I was quite scared as it got worse this morning so i went to the emergency room which cost me quite a bit. all risk are eliminated except iron deficiency and blood clot. I am waiting for the test result. 
Any one experience the same situation during their pregnancy?