soft cup and sexy time

so i haven't seen my boyfriend in 3 weeks because he lives in another state, 4 hours away. i'm seeing him this week and am starting to spot and i think my period is coming. i'm on the iud mirena so i can't manipulate my body by not skipping a week of hormone birth control. my boyfriend is REALLY good at eating me out and i only see him every 3 weeks.... if i got a soft cup would anything happen down there if he were to eat me out....? like any blood? if so i won't let him go down south but i really really want it.. like badly that's how good he is.