@Valentina he gets a little constipated at times, so I thought introducing other liquids in small amount could help. Especially in the summer heat. But he just makes a face and literally throws the cup away from him. Yesterday I bought unflavored pedialyte and surprisingly he seems to tolerate that. To me it tastes weird, like mineral water almost.
Cdc has a milestone app and I think it's helpful to have an idea of what to look for. If you're worried, talk to your pediatrician!
I would talk with the pediatrician. Drinking water is not really needed at this age, my baby wants the glass at times but she bites on it 😅 She doesn’t know any sign either. I would mostly worry about the crawling/sitting up from laying down because maybe your baby needs some extra work with a physical therapist.