Spider bite??

About 6 months ago, my husband and I were at our the cabin in the Rocky Mountains for the holidays. He woke up with what seems to have been a spider bite on his forearm, just above his wrist on the bony part. It swelled up about the size of a large marble and was very itchy. We never saw the spider, if that was what it was, but the cabin had been closed up for the fall and probably did have some.
The swelling and itching lasted about a week, and went away. Yesterday the same exact spot swelled back up and started itching. Any thoughts on what this was and what can be done about it?
Thanks so much for your time.

[National Jewish Health]

Spider bites often include lots of swelling and surrounding tissue damage.  I am uncertain as to what would cause that area to be activated again.  I would make sure that your husband doesn’t get large reactions to all insect bites as that is sometimes associated with chronic lymphocytic leukemia.