A.B.
All I could think is there must a sensory shock to his system. Is the water too hot or cold? Was it ever once too hot or cold and he still remembers that? I'd try sponging him in a baby tub a little longer instead of the big tub. Try to rinse him using a sponge or baby cloth. The pressure of the faucet and/or showerhead probably is too much for his sensitive skin. Try adding music to the experience (your singing) and/or talk him through. Maybe appealing to his other senses during the bath will help him. And it very well could just be a shock to him. One minute, he's cooing and playing and the next there's all of this water rushing onto his body. Some children have a tough time with transitioning to activities. Calm him after a bath with baby massage and see if we can create some new memories. Rock him and try to help him see this experience as relaxing and pleasurable. Then, if you've tried these techniques, and others I'm sure you'll read online, with no positive outcome, I'd raise the matter with his pediatrician. Have you checked his bottom and diaper area to see if there's diaper rash that might be irritating his skin? If he enjoyed it once or twice, then suddenly started reacting, I'd check the pattern. Did something change? Did he accidentally wet his face? My daughter for a long time hated having water hit her face. Still hates getting hair washed (now 5 years old!). Keep a journal, if you can, to see if factors are changing. Time of day, meal. Is he gassy or hungry before you're bathing him? Too many things that can effect his reaction to bathtime. He could be also very sleepy and the bath could be overstimulating. For some children, a morning bath might be better. As you can see, there are a lot of reasons this could be happening.