Oh, please get him to the vet asap! Even a simple tummy upset can dehydrate these toy breeds quickly and they can go downhill rapidly. Lady had diarrhea for about a day last fall. I was able to stop the diarrhea with Kaopectate, but she wouldn't eat and just slept like Nacho. I took her to the ER vet the next day and her electrolytes were so out of balance they told me she could go into cardiac arrest at any time.
I can promise you the longer you wait to take Nacho to the vet, the more expensive your bill will be.