FEDERAL Workers Comp

I am a recently retired federal employee who was injured in a job related auto accident. I have retained an attorney for the personal injury, but he knows nothing about the Federal workers comp portion. The accident was 3 years ago and I filed the necessary papers to Worketrs Comp, who accepted the claim. I received Continuation Of Pay for 3 weeks but never filed any additional claim and the WC case is closed. Shortly after the accident I was diagnosed with Rheumatoid Arthritis and the Doctor stated " that the accident caused RA with "reasonable medical certainty". Also, I have contiunuous medical treatment but it's being paid from my Health Insurance. As I am in "medically induced remission" with 2 previous "flares", could I apply for "lump sum payment" even though I currently have no symptoms. The MD states that this is a life long illness. Thanks for your time. Bob