Kitten Constipated or having problems with going to the bathroom.

Hello everyone, new kitten owner here. I use to have several cats long time ago but recently two little kittens have entered my life. 

I have 2 about 6 week old kittens. They are both eating dry food and water, sleeping a lot and I get them outside to run around a bit. But one of them that I noticed has problems going to the bathroom. He will act like he's going to go, meow and then his stomach will make a noise. He will keep doing this tilI put him in the litter box, (Which he can't find on his own?) Then he finally starts to go. But he still has a hard time and its mostly runny. I have check it for worms and I didn't see any. Mostly just food chunks. 

 HIs diet has just been dry cat food, some wet cat food, water and I fed him some milk 2 days ago and some vitamin milk my vet gave me. 

Was it something he ate or is he sick?

Also another question but not the main one, how can I get him to find the litter box on his own? He will just walk around aimlessly until I put him in it. Do I just have to keep putting him in it showing him where it is? Its not in a corner its just out in the open. 

Hi and welcome to TCS! 6 weeks is very young to be away from mom but circumstances do make that happen sometimes. He sounds like he is still learning to use the litter box. Hopefully it is low enough for him to get into easily. Also, it's important to use non-clumping litter with kittens who are still prone to tasting everything. Yeah, you just have to keep showing him where it is and when to use it until he gets the hang of it. A litter called Kitten Attract might be helpful to you.

I am concerned to hear about seeing food chunks in his feces. Recognizable food chunks means that the food is not being digested at all which is not normal. Dry food may be too hard on his digestive system. Wet food is much, much better for cats and especially young kittens (www.catinfo.org for more info on that). If he's having the same digestive problems with wet food, then there is something going on in his digestive tract and needs to see a vet.

I hope they are only going outside while supervised right now since they are very young to be outside alone. They may have parasites. Worms are not always visible in feces. If they came from an outdoor mommy, then they do probably need to be dewormed. It would be a good idea to have a vet check them out and get vaccinated soon since I think you are planning on them being indoor/outdoor cats? You can also schedule spay/neutering. Good luck with your new kittens.