I don’t know what to do

Help I don’t know what to do please don’t judge. I live with my in-laws to help my mother in law with cancer and my son is two weeks old today. Fleas. I can’t stand fleas and they won’t go away we have bombed the hole house multiple times before he got here and they have now evaded his once free room how do I safely get rid of them now? We had to bring an outside dog in for a few weeks even though I told them he needed treatment first and the fleas won’t go!