I have 5 ferral cats. 3 of them let me pet them. The one male cat even lets me hold him a little. Tonite he was not around for dinner so I waited for him. When he finally came home he was scared and afraid of me touching him. I finally was able to touch his tail  there is a large lump on the underneath that feels hard and seems very painful to him. It was not there this morning. What can I do to help him.