Why do i feel this way!!

Yesterday I had a cup of coffee half way through it i started feeling woozy, and just weak. Today about a hour ago i ate a toasted poptart with a half a cup of coffee and felt the same way i felt like yesterday but worse i felt like i was going to pass out and just felt really weak. I had to go lay down for a little bit i was also having a few lower cramps. I am fine now though. Anyone know what this sounds like? Im 26 weeks pregnant and never experienced this with my son.