Feaked out and now peed on the couch

I posted a couple days ago about my 2 yr old neutered male who freaked out and bit me when the air conditioner kicked on. After the incident he wouldn't go into the basement and was very jumpy. By last night he was doing very good playing again, etc., but still not the basement. Anyway this morning I came down stairs and he peed all over the couch. I searched previous posts and found causes were urinary infections or something is bothering them. It seems more likely this is recent incident was the problem (and because he peed right were I usually sit and was petting him last night) and I would like to deal with it before a stressfull vet visit (for him) that may make his problems worse.
How do I deal with the problem? I've only begun cleaning the couch, I don't know what to do.
I have had his litterbox upstairs since he bit me and became afraid of the basement and he was using it fine before he peed on the couch early this morning. The only change around the house is that my girlfriend went to Ohio on Tues., but we don't even think he likes her, I wasn't gone any longer than usual yesterday, no changes by me (daily brushing, petting, playing,treat,). We have had him since his eyes were barely open and this is the only time he has not used a litterbox.
Thank you for your advice.

I understand a vet trip might stress him out, but you need to rule out a urinary tract infection first, so you know your not dealing with that. Male cats are more prone to UTIs and they can appear suddenly. Call your vet and make him an appt. If the UTI is rules out, you can ask him about correcting the innapropraite urination. Good luck

Urinating on personal items (like clothing, the bed or the couch) is usually a response to a stressful situation. That airconditioner really freaked out your poor cat and then the lady of the house disappeared (maybe that noisy machine ate her!). You might run to your local pet store and purchase a Comfort Zone diffuser (they're expensive, but do a good job of calming frightened cats). And, if you have a health food store, purchase some Dr. Bach's Rescue Remedy which will also help calm your stressed out boy.

The Rescue Remedy can be mixed into a small amount of canned food so that you avoid the stress of putting it in his mouth. RR works amazingly well at calming anxious cats (and other critters).

Make sure you use an enzymatic cleanser to clean the couch. The enzymes actually remove the urine rather than just masking the smell.