I am 20 days post op and I have good and bad days. As each day goes by the good days are starting to outweigh the bad. Most of my issues are emotional in that I sometimes feel depressed also. I am struggling with getting my 60 grams of Protein and each day is a challenge. I am so tired of Protein shakes so I don't want to drink them but I am forcing myself because I have to. And when I can't reach that protein requirement I get sad and so frustrated with myself. Basically, I feel very much the same as you described. I think what can help you stay positive is to concentrate on your successes with the weight loss and take each day as a new day to do better ????.
As for the pain your are experiencing, I agree with most of the comments in that you should notify your surgeon. Good luck and great job on the weight loss!
Also, when I had trouble with Water, I found that ice worked wonders for me!