College is a big step. Whether you're commuting to school or live on campus. Along with college comes the stresses of school and "becoming an adult" and "living on your own". Not to leave out all of the other drama back home and now in your everyday life you cannot escape.
In one semester of college a lot can happen. I mean in most cases you have just moved a significant distance away from your family and friends, away from an area you've known your entire life. You have to start new. Find your place elsewhere. So you make new friends. Make your own little community. You also are faced with financial stresses. You know have to figure out how to pay for food and gas. Your parents probably aren't paying your phone bill anymore. You now have to decide what is more important, hanging out with your friends or studying for your literature exam. You're probably use to all nighters and can sleep through three alarms because you've gotten use to your loud hall. You may be quieter and more reserved because you don't have time to be upset. You might be stronger. Not just because you hit up the gym your tuition pays for, but because you've experienced a few things. You've seen struggle and hurt. You now know what it is like to be out of swipes for the day, no snacks, and starving. You know what it is like to live with someone you absolutely despise. You know that most people lack in manners and leave tooth paste spit on the sink and clumps of hair in the drain of the shower (and no they will never pick it out, nor will the janitor for your building). You most likely know what someone who hasn't showered in a few days smells like. Not to mention the garbage that sits in the hall for a week. You've seen drunk people. You've seen high people. You've heard some crazy stories about weekends and week nights, even during the day. You start thinking about yourself more which in my opinion is completely okay. You've definitely worried more.
A lot can happen in one semester at school let alone at home. You are growing into your own skin in a sense . You're finding yourself. Even if it is probably one of the most stressful situations known to man. So yes physical changes may occur, but that is just the process of "lifeing". The first semester of college is far from a walk in the park. It is more like a race with a cheetah, always trying to run fast enough so it doesn't take a nibble. The first like three months of school a lot is happening. So don't be surprised if people back home say you're different because you are and that's okay. Embrace your change.