Dog keeps humping my arm

[Soubriquet]

She's been doing it for about a week now.

Grabbing on her toys, trying to get me to play but as soon as she gets the chance her front paws clamp around my arm and she's humping away

I'm pushing her off every time but then she attempts to do a cushion or a pillow.

She's not spayed yet. Looking at getting her done after her next season. Why is she humping all the time though?

Maybe she's getting overexcited. Just walk away when she does it to your arm.
Give her a special "humping pillow" of her own to use, perhaps it'll calm her down.

Is she due a season? Has she had one yet, if so how long ago?