Vets appointment- is it necessary?

When I got my kitten the vet said she had slightly teary eyes as she had red crust in the inner corners. 

She pretty much grew out of this, with the ocaisional wipe her eyes looked fine.

The last few weeks we have taken her outside on a harness for the first time (she loves it! and miows to go back out all the time).

However, over the last few days I have noticed a dark red crust forming quite a lot (think dried blood colour) on the inside of one of her eyes. At the weekend I saw her with a big tear running down her  face (she looked soo sad () its the eye where the crust is.

She hasn't been herself the last week, fairly agressive which I put down to a change of environment for one day on Easter Sunday, however I am starting to think it could be the eye. 

I haven't seen her paw at it more than usual, so hard to tell.

I go on holiday on Friday so think I may take her to the vets before we go. 

However, I have been known to turn up and there not be anything wrong, just normal kitty behaviour etc. I am keen to avoid putting her through unnecessary stress of a trip to the vet as well as the financial cost for me. 

I have never owned a cat before so its all new to me, please could someone advise? 

Thanks in advance! 

Jo 

If you pull up upper eyelid by finger, you may see red thick inflamed 3rd eyelid (internal). This is conjunctivitis, needs prescription drops from veterinarian, add cost of visit ($70 here) too. It can be caused by 3 different types of microorganisms, each requires own treatment. Only 3rd (antiviral) worked for my cat, usual tetracycline (cats' concentration, not humans') caused aggravation of symptoms.

I would advice to get to your regular vet immediately, disease progresses fast. With a vet prescription drops, in a week it stops.

If accompanied by sneezing, may be Upper Respiratory Infection.

I'm not diagnosing, just sharing my recent experience with a new cat.