New 7 month old kitten suddenly fearful and hiding, plus eye problem

Hi, I am a new member and a new kitten owner. Please accept my apologies if I have posted this in the wrong place or if I am asking too much at once.

Yesterday I brought the kitten home. It is actually 7 months old, but I am told this is still classed as a 'kitten' in terms of food so unsure what term to use.

She immediately came out of her carry house and looked around. She explored the place, was very affectionate, played with me a lot. I had to put her back in her carry house for a brief time (ten minutes) and upon returning, I took her out again and she was like a completely different kitten. She ran and hid, under the radiator. She wasn't vicious, she was still extremely docile, but she was acting scared and fearful. I have no idea what caused this change. I stroked her under the radiator and tried to behave the same with her as I had before whilst she was playing with me, but after a minute or so she ran again, this time into a small hole under our television shelf (which I hadn't even realised was there as it is out of sight!) I didn't want to just take her out incase it frightened her, but after a couple of hours of attempting to coax her with food, treats, etc. I decided it was too cold for her and reached in and took her out.

She allowed me to do this, but as soon as I gave her to my girlfriend to hold for a moment she scampered away and hid somewhere else. I have now blocked up this hole and checked for others.

This is the first part of the saga - I am extremely troubled by the change in behaviour and can't understand why it happened.

The second issue is something I am wondering if it is the cause of the first. My girlfriend saw something in the kitten's eye this morning. We held her gently and got it out with cotton. As we did this my memory kicked in and I realised that the day before when she ran to hide under the radiator, I did see one of her eyes was semi-closed. At the time I thought it was because she was brushing her face up against the wall below the radiator. As we were cleaning her eye I also noticed some dark yellow mucus in the corner of her eye, the nose side.

I've read a small amount about this and I know this can be a sign of an eye infection or other things. I am now wondering if her sudden change in behaviour is a direct result of this eye issue. I am still at a complete loss as to how it happened though, as she was absolutely fine, playing with me gently, then she was in her carry house which was empty.

I really don't know where to start with these issues, as whilst she is acting scared of us and hiding under the bed, radiators, etc. it makes me concerned that if I disturb her by attempting to deal with the eye it will make her trust me less, but I'm obviously also concerned about her eye issue. Is this something I should let a vet deal with or could I clean it myself? Is it likely that her behaviour will change back to being playful and confident once it has been dealt with?

Sorry if this is a long ramble, but I'm confused and worried and feel it's always important to give the big picture!

I have inserted an image of her in one of her hiding corners that we took this morning. Her left eye can be seen here:

Hiding is a common behavior for a cat in a new home.  She's been taken from the familiar and put into a totally new environment with new sounds, new people, new smells, new everything!  To help her adjust, confine her to one room (like the bathroom or a spare bedroom, or even your room) for several days.  That way, you can be sure she uses the litter box, is eating well, and she can get used to you and your voice and smell.  You can leave out dry kibble for her, but when you go into the room to visit, take a serving of canned food with you so that she associates you with something good (food!).  It's possible that she has a little kitty cold.  Another very common thing brought on by the stress of the new environment.  Give her lots of patience and TLC to come around.  Don't force her to do anything she doesn't want to do, but let her set the pace on when she comes out and starts to explore the whole house. 

Hi, thank you for your reply.

It has put my mind at ease knowing that this is normal behaviour, as I thought I had done something wrong!

Some good news: last night my girlfriend started purring at the kitten and she responded by coming for some cuddles I was also able to join in - she is very affectionate!. She seemed much more comfortable, although still startled by noises. I have her in a bathroom and my bedroom area, which are linked together, so she has a fairly small area to be adjusting to. Last night I could hear her exploring, using her claws, and also using her litter box!

Thanks for your help.

Yep, just need to give her time to adjust.  She's such a beauty!!  Keep us posted on her progress.