Makes perfect sense to me matey.
I get the same feelings from time to time.
I think deep down inside, your mind is telling you that you need to think about sorting YOURSELF out.
Worrying about the troubles of others comes second because it will take up the energy needed for your own problems. It's an unconcious thing.
It's not a bad thing, or even a wrong thing, to think inwardly when you're in the dumps. Just keep a check on your emotions and feelings, keep in touch with them and when your problems do eventually even themselves out, you'll begin feeling that familiar concern for those around you again.
One thing I've learned though, is other people tend to flip out and make short sighted assumptions when my behaviour changes, so be sure your closest friends and family are aware that you're having a few problems, so when YOUR behaviour changes, he/she/they are prepared, rather than scratching their heads wondering.
It'll make your private battle easier too, knowing that they know to leave you alone when you need.