Comparison is a recipe for disaster and disappointment. I feel like a broken record saying this on these forums, but everbody and every BODY is different. If you are doing everything you are supposed to do and following your plan, you will lose weight. How quickly you do so is unbelievably irrelevant in the long run. I promise! I "only" lost 15 pounds my first month. I "only" lost 8 pounds my second month. I "only lost 5-6 pounds a month for several months after that. I "only" lost 2 pounds a month for several months after that. You know where all those "only"s got me? To goal where I've been maintaining for almost 16 months.
I promise you that I have never once looked back and thought to myself "too bad I didn't reach goal a month earlier like so-and-so did." It genuinely makes ZERO difference if you lose all the weight in 6 months or in 16 months. What matters is that you stick to the plan, get to goal, and then spend YEARS and YEARS living your happier, healthier life.
This isn't a diet. You will never be "done" with your sleeve. So there is no race to the "finish" line. This is the rest of your life!
Are you still taking pain meds or Tylenol? Any other meds like lipitor? It's possible it's just a normal reaction post-op. I think it could also be from not getting enough Protein. Hope it resolves soon.