How Can Swelling In The Penis Be Treated?

my husband and I tried using a new sex toy during intercourse it was a rubber ring that fits snugly around the penis and scrodum and is supost to restrict the the urge to pre-term ejaculate well my husband left it on his penis for several hours during our intimate time , and once removed, later on he noticed a enlarged vein that was starting to become a little tender and uncomfortable. then a few hours later after he noticed a swelling directly under the skin around the head of his penis somewhat to the side. it has been several weeks and this is still present it has never gone away. no pain a little sorness with stimulation at times but no other problems at all. what could this be and is it safe to continue intercourse if this has not gone away but not causing any pain or problems?