Intermittent Litter Box Issues - Please help me figure this out!

I have two male Himalayans, Purrcy and Jaspurr, who have been with me since they were 12 weeks old.  They are now 7 1/2.  They have always been very bonded and have never been separated.  A week ago Purrcy was frequenting the litter box more than usual and I was not seeing much urine.  I took him to the vet who examined him and said he was not obstructed but his bladder was empty so she could not get a sample.  She said if things did not improve or got worse to bring him back.  When we got home from the vet I let Purrcy out of the carrier and Jaspurr started hissing and growling at him.  I suppose the dreaded vet smell.  The aggression, although not physical, has been very stressful for both me and Purrcy.  But things have been OK with the litter box situation - until today.  This morning I noticed Purrcy visiting the box and he went about three times in 15 minutes.  But that was 7-8 hours ago and he hasn't been back in there since!  He has been asleep most of the day.  There has been absolutely no signs of distress or pain.  No vocalization at all.  No peeing outside the box.  No licking. He is eating and drinking.  He just seems bewildered that his brother is treating him so poorly and I know that has been hard on him.  He continues to try and "make friends" with Jaspurr and even though the hissing and growling has stopped Jaspurr still does the stare down until poor little Purrcy backs off.  I think Jaspurr has decided he has become top kitty and he's not giving up that position!  

Anyhow, obviously I don't want to have to take them back to the vet clinic and start the war all over again.  Although I have wondered if taking BOTH of them might help the situation.  (I won't ever just take one of them alone again.)  I just can't imagine that the urinary issues are due to an infection since he went almost a week without experiencing it again.  WHAT do I need to do????  I am considering having a mobile vet come to our house to do a cystocentesis.  HELP PLEASE!!

So, NOBODY has an opinion about this?  My point is that stress is not good for the urinary issues.  If I take them back to the vet there will be more stress when we get home.  Would a mobile vet be a better idea or would her presence just leave more scent in the house that would be as bad or worse?  

If he is still having issues urinating, you need to take him back to the vet to make sure he is not blocked.  I have three cats and one of them was blocked.  The other two would hiss and run when he came back from the vet, but it dissipates....I would keep them separated for a few hours after coming back and give both of them a treat and lots of praises if they are together in the room with no hissing.  Time is really of the essence here when you are dealing with UTI issues...we almost lost our little guy and had to do the PU surgery and he is recovering now.

Thanks for responding. 

I would have the mobile vet come if at all possible, you are lucky to have one. If your Purrcy's bladder was empty at the vets it doesn't sound like a blockage, but could still be the kidneys. I myself would encourage a lot of drinking and monitor closely to see if he goes. Some cats only go a couple of times a day. If he won't drink water, offer tuna juice, or ANYTHING liquid to keep him hydrated and going. Also, I take both my cats to the vet every time, just to avoid what you are taking about, even if it means one just sits in his carrier, they both get the smells and scary situation then and don't hate each other. Good luck, and keep us posted!

Sorry i cant help you on that one. But woud like to say hello as i am new here.
You must be very worried about your cat. Hope he gets better soon.