There does appear to be a trend toward restriction from November to June, but these are relatively small changes and, I agree, could well be attributable to changes in your abdominal musculature and less than optimum strength of your diaphragm. In essence, these changes are, in all probability, surgery related.
I would be reluctant to speculate on there being any actual change in your lungs themselves and, with a recent, Nov. 2008, negative CT Scan I would seriously doubt that the cause is some type of interstitial lung disease. A “fast systemic disease that is causing restriction” should be evident in other ways and I gather that the rheumatologist does not believe that such disease is a cause of your shortness of breath or your other symptoms.
The sed rate of 48, while non-specific, is not so easily discounted, and warrants further investigation. I wonder if it might not be an indicator of inflammatory bowel disease, perhaps of small bowel and perhaps also related to what sounds like spontaneous colon rupture. You have reason to be worried that you may have some type of autoimmune disease and I suggest that you stay in close touch with the rheumatologist, with frequent follow-up visits.
The PFT’s are of much less concern to me than is the drastic reduction in exercise capacity (30 minutes down to 2 minutes). This is very worrisome, deserves an explanation and, with the information you have provided, very unlikely to be on the basis of undiagnosed restrictive lung disease. In addition to some measure of post-operative abdominal discomfort that could alter your PFT’s, another possible cause would be paresis or paralysis of a hemi-diaphragm and that could account for a significant loss of exercise capacity. You should definitely have a chest X-ray to look for this because an X-ray may reveal some other previously unsuspected lung problem.
The most important diagnosis to be considered, and one that could easily account for your shortness of breath with minimal exercise, is pulmonary embolism (clots to the lung) which may have occurred following surgery and, for that matter, may still be occurring. This possibility should be evaluated with a D-dimer test and a spiral CT Scan, the latter also providing data on interstitial lung disease or other restrictive lung diseases. I suggest that you discuss this with your doctors, especially with your pulmonary doctor, as this is a diagnosis that must not be missed.
Good luck