I'm having trouble breathing after a hard fall, but don't think I broke a rib?

I took a very hard fall off my bike on Sunday. My arms and legs are covered in bruises and I'm sore all over. I can live with that. But starting about 5 hours after the fall, I started having to breathe very shallowly. Now, not too long ago I cracked a rib, and remember clearly how badly that hurt, not just to laugh or cough, but just to move. This injury isn't so bad. I can move around. But even walking up 1 flight of stairs, I have to sit down after and catch my breath for a good 5 minutes! Even if I talk for more than a few minutes I lose my breath. And it's not like I'm normally in bad shape. I'm hesitant to go to the Dr. because when I cracked my rib it cost me over $800 to find out that it was indeed cracked and they just gave me some ibruprofin and sent me home. But this shallow, painfull breathing thing is freaking me out! Anyone have this happen before? thanks!