A Friend Had Pneumonia The First Of June, Was Very

a friend had pneumonia the first of June, was very sick for about 8 days. He began having similar problems again about 1 1/2 week ago. He fainted and was admitted into the hospital. He's had several CAT scans, MRI, EKGs, spinal tap... tested for limes disease, rocky mtn spotted fever, HIV, all negative. Dr's have suspected lymphoma, no enlarged lymph nodes were found in his chest area. And he has lost 20 lbs since the first of June.
Do you have any suggestions as to what we need to be looking for now?