Your doctors seem to be doing the right things to diagnose your problems. So many suffer with inexperienced docs and are not diagnosed or treated for years. Early diagnosis and aggressive treatment are important for a good prognosis.
Treatment for MCTD is typically prednisone at first and then some pred sparing med like imuran or methotrexate. I don't know how mctd is treated when someone has sjogrens. My docs first started the quest in Sep 2004 and it was Oct 2005 before they got a positive diagnosis of mctd. Along they way they guessed I had lupus before the first symptoms. My labs showed very low platelets and mild anemia and the hematologist deduced I had lupus after eliminating other possible causes. 2 months later the first symptoms appeared and lupus was diagnosed shortly after....then mctd 2 months later.
It was also suspected I had pulmonary hypertension but a right heart catherization showed I did not. My breathing problems were due to weakened muscles and was imitating PH. Your doctors seem to be on top of things if they are testing for that...most docs would not know to do that.
MCTD (lupus, scleroderma, polymyositis). Diagnosed 2005. Kidney, liver, GI tract, dysphagia, raynauds, Barretts esophagus, quadriplegic in 2005. Recovered and now active in skiing, tai, chi, hiking, golf. Meds: prednisone 2.5mg, imuran 50mg, amlodipine, benazapril, omeprazole, potassium, folic acid, vitamins, maxide and various supplements and vitamins.
Remain optimistic and you can overcome the odds.