Even with your gall bladder removed you can still get a stone stuck in the remaining duct. This requires a special imaging to be done to detect this an ultrasound will not see this. If that is the case then surgery is a possibility to remove it.
ANother possibility would be a peptic ulcer that is referring pain to the right side. This would need treatment with medication.
Both situations require and evaluation by your provider and I encourage you to see your provider without delay and both situations can worsen.