Last night several times one of my cats made a weird noise(I'm sorry, I don't know how to describe it) that he'd never made before. Today he has been lying in one of the litter boxes throughout the day. He has never done this before. I don't think he has eaten anything today. I found regurgitated food (undigested) this morning. He let me pick him up but seemed tense. What should I do or watch for? He let me touch his extremities and pet him and I didn't find anything unusual.

