Well, for starters you've over-loaded your system and now your body is trying to deal with moving all this food thru you! Never do this again, if you want to gain weight increase your food intake slowly over time. I would drink plenty of water to help move this a long and eat lightly until your stomach is no longer bloated. If you don't have any BM's and are in pain, go to the ER.
Somehow it feels like there's nothing moving anymore... Is this possible?
I don't know..you could have shocked your system so to speak. I'm very skinny too and also want to gain weight. I was told to drink ensure with each meal to try and gain weight..I haven't tried it yet but will be getting it soon. It was doctor recommended and its apparently used with people who are recovering from eating disorders and chemo patients to help them gain weight. Have you tried a stool softener? It may help.
Welcome to the gastroenterology community! It is a very bad idea to eat way more than your body tells you to all of a sudden. As mammo said, if you stop having bowel movements you need to go to the ER. It is hard to tell if it feels like there is nothing moving so I wouldn't worry too much about that (you said it is making loud noises which means things are moving). I wouldn't recommend a stool softener at this stage, but if you feel rectal pressure and can't get it out you can try a warm water enema. Good luck.
Thank you guys. The pain has gone but my belly still looks the same is still hard and I'm really getting hungry now. Do you think I can eat like that? How can I know whether bowel movements have stopped? And more important: why does it cause such problems if I eat as much as most people do during a day?
You can eat but it in small amount with foods that are easy to digest. Eat smaller meals and eat them more frequently if needed. If you don't have a bowel movement for a couple of days (or longer if you normally only have bowel movement every couple of days) then you need to get checked out. If the pain has gone done, then you most likely are going to be fine.
The problem is not how much you ate; the problem is really that you ate a lot more than usual all of a sudden. If you had slowly worked up to eating a lot every day you probably wouldn't have had any problems.