Can you talk to your friend or write a text/email? Let her know what is going on and you feel sad and want to crawl away from the world. It sounds like this person is important to you and you want them to be around.

Seeing a therapist or doctor may help you determine is this is depression you are feeling. From what you describe it is. LAck of motivation, feelings of guilt, lots of sadness, over sleeping. There can be situation causes but there can also be the depression always there and little things may bring it out.

Medications have helped my physical symptoms. The tiredness, fatigue, difficulty concentrating anf making decisions. You won't know if medications are right for you unless you talk to a professional.

Therapy has helped me deal with some things that worsen my depression. At first I had a hard time to describe what I felt, and sometimes I felt nothing, like I was empty.

To find a doc/therapist you can probably go to your school's resource center. A lot of school's have counselors that or mental health programs that can help students. If you don't want to do that you can find local psychiatrist or psychologists that you could talk to. A website like healthgrades.com may help.

the best things to do is to take care of yourself even if you don't want to. Like make sure you eat healthily (i.e. don't binge eat for comfort or don't skip meals because your appetite is gone.) A lot of people find exercise and fresh air helps them. Try to reduce an stressors in your life you can. If a class is too difficult and you can't deal with it right now, maybe drop that class for a semester and come back to it.

It's hard to explain how depression feels. Some people have had some situation sadnees (like a family member dying) and think they understand depression. That is as close to saying going to the olive garden is like going to Italy.

Be honest with her and if you don't know something, it is ok to tell her that. Withdrawing can come off as like you don't want to be their friend from the other person point of view. Try to tell her how you feel and what you are going through isn't because of her or any reason that you know of.