How do i have multiple orgasms??

My bf gives me oral and then i can easily orgasm in like 15min,but then i get too sensitive and tense and i can't continue. I tried to wait a min and continue but i still can't come.. The sensitivity is gone but i cant build up the pleasure like the first time?

The most I've come was 2 times but 2-3hrs apart one from oral one from masterbating myself, not in one session...

Any help ladies?