Avoiding shoulder and back pain takes some planning. Heavy textbooks and backpacks are a recipe for shoulder and back pain. Most college instructors expect students to have their textbooks with them in class. On large campuses, where parking is limited and often a long distance from classes, this means you have to carry most of the books you need for the day with you. Unfortunately, this makes it almost impossible to avoid shoulder and back pain, unless you are careful when purchasing bookbags. First, you should never, never use a regular student backpack. While these are the most common method of carrying books, followed by book bags that are similar to laptop bags with handles and shoulder straps, these are the most dangerous to your physical health.
The best answer to this type of shoulder and back pain I have found is to purchase a bookbag/backpack that has wheels and an extention handle. While these rolling backpacks are a pain on stairs, they work well everywhere else, and even dealing the occasional stairs is better than having a constant strain on back and shoulders. The Olympia 19" Rolling Backpack is a good choice, but you can find others that will work just as well in avoiding shoulder and back pain.