Is it normal to feel an empty urge in your rear when aroused (gay guy)?

it doesn't make any sense i guess but when i'm turned on i feel like almost like my ass is a vagina >.< (though i wouldn't know) it's an empty ache to be filled, i'm not sure if my body just adapted after so much fingering or what lol. it could be a medical issue i guess? which is why i'm worried. so i wanna know which it is

thanks