I have no doubt your cat knows where to go when his tummy starts talking. Best wishes to you. I'm sorry you have to go through this.
My own Mr. Jingles used to be a stray, and he always turned up like clockwork on our porch twice a day. Occasionally he would be gone for a couple of days straight and my wife would get worried... but then he would turn up out of the blue all scratched up from fighting other strays. The food we were setting out attracted the other cats, and neither hell nor high water would chase Jingles out of his territory. His leg would be all cut up and bloody, he would have scrathes and bite marks on his head and above his eye. His left eye doen't open all the way now, giving him a gangster Lucky Luciano look which totally suits him. Anyway, we had to start bringing Jingles in for the night and he would eat, sleep, receive some nursing, and in the morning yowl like crazy to go back outside, knowing full good and well trouble lurked out there. He didn't care one bit. Eventually we had to shell out the money to have him neutered and get him all his shots because we couldn't stand him getting in fights and coming home hurt every night. He's now happy and spoiled, and no longer yowls to go out. But every now and then I'll catch him gazing out the window, thinking about outside.