Struggling with dehydration, extreme fatigue, headache, upper back & shoulder pain, my surgery was 7/11/18, is this a concern?

At just two weeks post-op, it’s not uncommon to experience some fatigue and adjustment-related symptoms. However, the issues you're describing—dehydration, extreme fatigue, headaches, and upper back/shoulder pain—do raise some concerns that should be taken seriously.
Dehydration is one of the most common challenges after bariatric surgery, especially in the first few weeks when your fluid intake is limited. It can cause all of the symptoms you've mentioned: headaches, fatigue, and even body aches. The pain in your upper back and shoulder area could be referred pain from gas used during surgery, or it could relate to postural changes, but it’s also important to rule out more serious concerns such as gallbladder issues, a developing infection, or a possible leak—although the latter is less common and usually presents earlier with more acute symptoms.
That said, persistent fatigue and shoulder pain at this stage should never be ignored. I would strongly recommend contacting your bariatric team or surgeon immediately for a thorough check-up. They may want to run some blood work, assess your hydration status, and possibly order imaging to rule out any complications.
In the meantime, please try to focus on small, frequent sips of water throughout the day, and avoid waiting until you feel thirsty. If fluids aren’t staying down or you’re not passing urine regularly, that’s a sign you may need IV hydration.
You’re still in the very early stages of healing, and it’s okay to ask for help. Your health and safety come first—don’t hesitate to get in touch with your care team as soon as possible.

Hello, after reading your information I would definitely consider the case for an evaluation.
The first thing is that you must evaluate yourself with a certified bariatric surgeon to review your case and then proceed to check you.  There are a lot of factors that can be and should be considered before giving any exact information. Make sure to discuss this with your primary physician. Keep in close contact with your surgeon and go to support groups. 
My Best Wishes,