I’m 6 weeks post op and was going through the same. Was a roller coaster someday ms were good for energy and some weren’t and some were half and half, such as the morning I felt energetic in the morning then after lunch the 2nd half of day I was just crash. So I was told from my dr/surgeon it was I needed more protein. So now he has me doing protein shake for breakfast , lunch and for dinner I can have something else. And of course water nothing else. And sure enough it’s doing the job for me. But overall I understand you. Maybe try more protein.