please help, cramps and sickness after sex! feel like I'm gonna pass out!

So I'm 18 weeks and just had sex with hubby. I'm now sat on the toilet with cramps and sickness. It eases off but as soon as I go to lie back down the cramps come back and the sickness. I keep feeling like I'm going to pass out!! Help!! 
I keep getting contractions, is that normal? Will they pass?