SWELLING OF LEFT ARM & NOW LEFT KNEE AND CALF & ANKLE

i REALLY DO NOT KNOW WHAT Category to put this under, I hope someone could help me on it. My husband has been having some swelling issues lately his left forearm a couple of weeks ago swelled up pretty good and he told me it was a spider bite, (he is a Plumber climbs under houses alot) But I did not see any kind of bite on him, well it swelled up almost like he was retaining water, for a bout a week then it was gone, Then about a week later his left knee was hurting pretty bad then that swelled up his calf and ankle swelled up so bad you cannot even see his ankle, could some please give me some ideas on what it is.
Stella Peltier