Hi! Yesterday I Went White Water Rafting And Obviously Had

hi! yesterday I went white water rafting and obviously had to paddle along with the raft! today I have pains in the "V's" of my hands between my thumb and index finger, which I think is from rowing. this has been going on all day but just now I noticed a vein that is bumped up in my hand. it is not abby different in color, and it is not painful to push on it. do you think this is just from rowing in the raft, or do you think it's something other then a vein? thanks!