3rd eyelid showing, cat is a little mopey.

On May 9th we got a new kitten. The kitten was vetted prior to coming and other than a few token fleas is a healthy little girl. The past week our 3 year old male cat has been acting mopey and not himself. He fussed with his ears a lot one day but they are clean/have no smell/he has no nasal or eye discharge/breathing normal/eating and toileting normal. He has a little bit of an allergy issue and I just chalked the ear up to that. There was also a day two weeks ago that both of the older cats were sneezing (no nasal or eye discharge at all) some but it was mostly our 9-year-old cat and by the next day all sneezing stopped.

Today he has had his 3rd eyelids about 1/4th out all day and isnt his usual peppy self. I am worried it may be stress from the new kitten getting him down. She seems to have a knack for settleing into HIS favorite spots. I'm also a little worried he may be sick, but there are no other symptoms and I (understandbly, imo) don't want to drop $60+ at the vet for nothing.

I picked up some calming treats and am thinking i'll get some Bach's Rescue Remedy, too. If he were to pop up with a real solid symptom I would whisk him to the vet right away. I'm worried but I also feel foolish because he might really just be throwing a little fit.

Any advice would be appreciated.

I would take him to the vet. The third eyelids don't come out for no reason. Let us know what you decide!

He started sounding a little congested this morning so we went to see the vet. He has a virus flare up brought on my stress from his new sister. His prize was a shot in the rump and some treat flavored antibiotic drops twice a day. Thank you so much your reply!