jollor, My husband has had the same problem a couple of times. He is almost 6 months post tx and I did call transplant doctor and GP when this happened. They both said that he needed to drink more, he was becoming dehydrated. It did seem to do the trick, my husband had his stent for about 6 weeks and they said that it often irritates, especially men, sorry. DRINK, DRINK, DRINK.
And by all means, get your labs done and fax to transplant coordinator for them to check. Take care, and keep us posted.