Can you give probiotics to animals for digestion or for yeast infections in the ears? I…

Before any product is given, I usually recommend you consult your veterinarian. My concern for your cat based on what you've described is that he is constipated. With constipation many cats will have straining followed by diarrhea. This is because they push down loose stool around the constipated part. This may also explain the puckering of his bottom. If he is constipated, a probiotic, cat lax or digestive enzyme will likely not help.

Probiotics can be used for some medical conditions but the first thing is to know for sure what condition you're dealing with and if a probiotic is the best option for treatment. There are some cases where handling a condition "naturally" is appropriate and I am certainly not opposed to that but from what you describe I feel your cat may need additional care. Good luck.