vsg nausea 4 days post op

Ive been having a hard time with maintaining my 64 oz of water daily but I am walking fine and moving.  Recently I started my protein ready to drink muscle milk.... I had about 4 oz in about 20ish mins... im feeling really sick now... headache and nausea gurgling in my stomach and chest/throat.... 

Is this normal? Does this subside? 

I wasn't able to drink my protein drinks until I was about a week post op because they made me super nauseous. After that, I was able to drink them but I had to drink them really slow; It took me about an hour and a half to drink 8 oz. I was told that early out, you should focus more on your water intake and worry less about your protein. It will get easier to get your protein in when your stomach is a bit more healed and the nausea and gurgling subsides.