the swelling in any bug bite
is an allergic reaction
associated with inflammation. This condition usually subsides on it's own. In your husbands case the allergic reaction appears to be regressing, but the inflammation appears to be still persistent. Moreover, the presence of pus suggests ongoing infection. It is important that you get yourself checked by a surgeon, just to rule out underlying pus pocket and to start an antibiotic if needed. Also, he may need a dressing to be done till the condition heals.