I'm having trouble taking deep breaths lately. Sometimes I can manage it, but I mostly end up breathing through my mouth. This has been going on for about three weeks. I used to have other issues like stiffness in my fingers in the morning and pain in my right shoulder and upper arm, but those have either gone away or are getting better. I had a blood test back in January that showed high ESR and low platelets, but I feel okay now except for the deep breathing issue. What could be causing this?