Bump on Hand

Sophia β€’ TTC baby #1 for 5 years. IVF #1 FET ended with a D&C @ 9 weeks in 2016 😞 Have an πŸ‘ΌπŸ» in heaven. IVF #2 January 26, 2018 πŸ™πŸ» Got pregnant with twins πŸ’•πŸ™πŸ» went into preterm labor in June 2018 and delivered 25 week premies. My life is now complete.
Hi ladies, I need your help. A few days ago randomly on my poor hubby's hand this bump appeared. It hurts when he presses on it but he doesn't know what it could be. Any idea why this happened or what it is?????