constipated from prenatal vitamins

The doctor gave me a bunch of sample packs to take to see which prenatal vitamins I like... last night I took one that was a double pill didn't realIze what the second pill was for... today I am so constipated my stomach hurts, feels very full and extremely bloated! I'm only 8 weeks and today I feel super pregnant! I looked at the pack just now and it has 90 mg of iron and that second pill is a stool softer! Ughhhhh