What Causes Sickness Immediately After Intercourse?

I went on the pill for the first time, which were microgynon, and i have unprotected sex with my boyfriend all the time, after being on the microgynon for a month i had to change because it was very bad for my skin, i then changed to yasmin without my 7day break, which is what the docter advised me, yasmin has been better for me it has cleared my skin, but the other day after having sex with my boyfriend i was sick straight after and i couldnt stand up? whats wrong with me!:((((( i'm only 19