What is causing upper thigh pain after gallbladder is removed?

The symptoms you're describing, particularly the rash and the burning sensation in your thigh, are not typical after gallbladder removal. Here are some potential considerations:

Allergic Reaction: It's possible you could have had a reaction to medications or materials used during or after the surgery. The rash on your midsection could be indicative of an allergic response. Some people can develop allergies to antibiotics, pain medications, or even surgical dressings and adhesive tapes.
Nerve Irritation: Sometimes surgical procedures can inadvertently irritate or injure nearby nerves, causing pain or altered sensations. However, the relationship between gallbladder surgery and a sensation in the thigh isn't direct, making this a less likely scenario.
Surgical Site Infection: Any surgery can potentially result in an infection, though your description doesn't sound typical for an infection. Still, it's something that needs to be ruled out.
Secondary Conditions: It's also worth considering if any other conditions, not related to the surgery, have developed coincidentally.
Referred Pain: Sometimes, pain can be felt in a different location than where the problem is actually occurring. This is called referred pain. However, this typically wouldn't manifest as a burning or stinging sensation in the thigh after a gallbladder surgery.

It's essential to closely monitor your symptoms, and if they worsen or if you develop new symptoms like fever, increasing pain, or other unusual changes, you should seek medical attention promptly. It's also crucial to keep your scheduled appointment with your surgeon, and you might consider asking for an earlier appointment or a referral to another specialist if the symptoms are concerning or worsening.