My cat kneads non stop?

I found this cat 2 days ago on the side of the road in the middle of nowhere land and we brought him home but for some reason hes been kneading like crazy.When we pick him up he kneads in the air...Hes kinda still a baby.I was wondering if he had a problem or because it was taken from the mother and and then thrown outside?Just was wondering cause me and my husband were having a debate about it.