I call that the "Lonelies". It comes like ghosts or something. The loneliness can surround you and swallow you up at times. It can be maddening to go out to try and connect. That can magnify the feeling even more at times. The one thing I've found is it does come and go. Perhaps your "Lonelies" are stronger then mine, but it's all in your head to a degree. Try to recognize and understand the feeling, because it truly is a feeling. Detach yourself from the feeling, step away and look at it so you can see what it is so when the "Lonelies" come you can look at them and deal with it better. For lack of a more scientific term it is sort of like a "Demon" and I'm sure you've heard the term before that people have to deal with their demons because we all have them. Rest assurred that you are not alone in your loneliness, don't ever think for a moment that millions of people don't feel the same way everyday. The horrible feeling of being alone is in everyone's DNA through natural selection over billions of years. Those who went off alone, through the ages, died and did not reproduce. The rest of the species survived to reproduce because the fear of being alone kept them safer in numbers. The fear of being alone is almost a survival instinct thing, so be thankful that you have survival instincts. Find a good Therapist if you can and talk it out with a professional. Save those loneliness thoughts for your Therapist, or this forum, because the last thing you want to tell people is that your lonely cause it doesn't help solve the problem and may well keep people away. I understand how over powering the feeling can be, but obviously you can cope with this because your in MED school that is an extremely remarkable accomplishment. When you begin to feel over powered by the feeling my suggestion is to do soemthing good for someone else no matter how small it is. Force yourself to some how help some one else or some other creature. Feed some pigeons, give a dollar to a homeless person, leave some small amount of money in a poor area, then leave, think of the wonder and happiness you brought to whom ever found it. Find some poor soul worse then you and provide some small comfort. You will be surprised at how this makes that nasty "Demon" run for the hills. What you truly want is love and by giving love without expecting in return you defeat loneliness. It goes away.