My Girlfriend Is Experiencing Period Like Cramps A Week Before

My girlfriend is experiencing period like cramps a week before her period is supposed to start. In the past, she's only felt them a day or two before her period. She's been on the birth control pill for about a year now. She took the pill about an hour late a couple days earlier this cycle, but aside from that, hasn't missed it or anything. We had sex about 10 days ago, and I finished inside her. She's also been traveling a fair amount and has eaten fattier food than usual. Do you think the cramps are a pregnancy sign or a reaction to the change in diet/routine?