In my experience, the worst part of this feeling is that it's compounded by guilt at not doing what you "should" be doing or feeling what you "should" be feeling in a foreign country. I like what the person above suggested about room service/cable TV and other comforts like that. Work toward getting out there and exploring but don't beat yourself up about it. Just do what you need to do at the moment to feel good and, most likely, the rest will pass.