Why does one of my rats have bad diarrea?

I have 2 male rats and one has bad diarrea, all i have in their cage to eat is yogurt which they eat all the time,and rat block pellets,and some celery and carrots and they have their water bottle of course, i dont know whats wrongWhy does one of my rats have bad diarrea?
maybe the rat has more of a sweet tooth than your other rat and chooses to eat the vegetables and yoghurt over the block pellets. i would suggest to limit the amount of fruit, veggie, and yoghurt and keep track on how much of that you feed him. This will prevent him from having diarrheaWhy does one of my rats have bad diarrea?
dont feed them so much yogurt, it will in the least make them fat and is probably causing the problem, rats arent even sopposed to have that much dairy. Use it as a once week snack. try feeding them more mixed nuts and some fruit because the blocks dont always have everything they need.





I feed my boys organic fruit and veggie baby food because its cheap, easy to prepare, and full of vitamins and carbs to give them energy. But usually not everyday. they also eat un-salted trail mix and I throw some blocks in too but they normally dont eat them because I would assume their not as tasty. Would you wanna eat that? lol
too much fruit 'n' veggies nooooooooo yogurt should be given they can't digest it, more rat food, but if ya wanna give em yogurt give them specially formulated yogies find em at a pet store don't fret about diarrea if it's not too bad my hamster had it for about 5 days then she was fine and dandy.