I Have Severe Constipation Verified By Xray On 5-27-16. I

I have severe constipation verified by xray on 5-27-16. I have lung problems and xray on 5/27/16 stated no obstruction but lung capacity is now shallower than last xray. I have a CT scan scheduled for 6-13-16. I have history of lymphoma dated back to early January 2001 that affected lungs and stomach. My stomach measures 62" I look like I am 9 months pregnant. A FOBT test on 5/27/16 was positive. What could be causing my stomach swelling and constipation? Lymphoma? My current constipation medicine isn't working Miralax, Colace, prune juice, citrucel fiber, drinking hot beverages. Any suggestions?