I've missed my period for 5 days, which is unusual since I typically have regular cycles. Recently, I traveled to the North for 10 days, where I experienced changes in my diet and water intake. I was also physically active, walking and climbing a lot. Despite these changes, I'm not experiencing any symptoms. I've taken a pregnancy test, which came back negative. I'm concerned about the delay in my period and would appreciate guidance or advice on what could be causing it.