male humping

[Floppysquirrel04]

hi! for about a year now i've been having a problem with my male FS. about 7-9 months ago, his balls got very large, and he started humping my arm whenever he could. I know humping is probably natural, and he is about 2 years old. but it has gotten to the point where i constantly have visible red scratches all up and down my arm. i can't play with him without him humping me. and what about the balls problem? they are about the size of his head, maybe a little bigger. usually. whenever he looks down, they look smaller and normal sized, but whenever he looks up, they get very big and stay that way for a long time. help?