Should I be concerned about my weird symptoms?

[JulesYndr]

For the last couple of years (I don't even remember when it started) I lost my appetite completely. I don't feel hungry anymore. I eat on the same hours every day, three times a day, but never feel the hunger. When I occasionally forget to eat, very long hours pass before I feel that my stomach hurts really badly and then I know it's time to eat, but even then there's no much of a hunger- more like my stomach starts to eat itself because I don't feed it.
Lately (for 2 weeks now), I noticed something very concerning. After each time I eat, I almost instantly go to the bathroom and have a slight diarrhea. With each day, the diarrhea gets worse. And it feels like everything I ate goes to waste just like that. Today I was eating lunch for about 20 minutes and about 5 minutes after I finished it, I went straight to the bathroom and felt I just (excuse me for the phrase) crapped it all right there and then. It can't be right though? I thought it takes long hours before meals are digested.
I'm usually quite healthy, eat and drink properly. Could what I described be a problem and should I go see a doctor about that? Also, if it could indicate a problem, what might it be?