How Can A Forearm Lump With Bruising Be Treated?

my husband did not hurt his forearm but it just got purple with a hard lump in the middle of the bruised area. the lump is black but is not hot nor does it hurt. He feels fine and has no fever. After two days it is still purple but the lump is yellow and green. We went to the e.r. this morning and the doctor said it is nothing to worry about just a bruise...no clot or bug bite. My husband just can't believe this. Should we be satisfied with the verdict? my husband is 70 years old, in good health, but has had open heart surgery 7 years ago and takes digoxin, enalapril, metoprolol, baby aspirin and levoxyl. none of these should cause bruising. He is 5 foot 8 in. and weighs 140 lbs.