Something Isn't Right

So I have a baby who just isn't acting like himself today. He is crying and whining alot and just isn't happy. I know some of you are probably saying "well he is only 10 months he isn't going to always be happy?" If you knew Braydon though you would understand that this child is almost always happy. I can usually understand why he is crying and easily solve the problem. His usual reasons are; tired, hungry, hurt, or wanting to be held. This time though nothing would solve the problem. He eventually went down for a nap and after the nap I went to change his diaper and found the problem. He had a serious diaper rash! Braydon is 10 months old and has never had diaper rash. I know we are lucky that he hasn't! I put Desitin on his bottom and he screamed during the whole thing. I feel so bad that he is going through this, I just hope it passes by really fast!