I bought a 350 lb calf at an auction. They claimed he had been weaned for a month. I could not find out what he was being fed so I took him home and started him on a calf starter grain mix from my local elevator and hay. He did fine for about a week and then one day he was just laying down and was real hard to get up. Once I did get him up he seemed bloated and had diarrhea and gas. I took him off the grain and fed just hay. He got better so I added back the grain. Again he got diarrhea and seemed real weak. I took the grain away and now just eating hay. Been about 1 month on just hay and he still acts real weak. Any ideas what might be going on or what I might need to do?