What could be causing a low white-blood, red-blood, and low-platelet counts in a former cancer patient?
Low red blood cell counts and low platelet counts are side effects of chemotherapy because the chemotherapy drugs kill off the fast-growing bone marrow cells that boost red and white blood cell counts.
If your dad is not currently undergoing chemotherapy, it means it's not the chemotherapy drugs that are causing this, so you need to have your dad see his doctor and run tests to search for the cause. Follow-up care and treatment after non-Hodgkins lymphoma is very important as it can recur.