My 84 Yrs Old Husband Had Pleura Biopsy 2 Wks

My 84 yrs old husband had Pleura Biopsy 2 wks ago today. Since then his breathing has been much worse than before the procedure..We have returned to the hospital twice and they have done blood work, ct scan, ultra sound, xrays and they all come back negative. Nobody has an answer as to why he is so short of breath. Do you have any suggestions - we are at our wits end as we expected him to be much better after than before and he is much worse...