Hi Anne: This is a tough one. It is a lot easier to say what is not – it is not GBS. GBS causes weakness with only minimal sensory loss and, although pain can certainly occur, it does cause this kind of pain. There is a condition called sensory neuronopathy which can come on after an infection, assuming the gastritis was an infection, and that can look a little like this. Sensory neuronopathy can also occur with a condition called Sjogren’s syndrome which could be the only link I can think of to a positive ANA. It is early days yet, just 6 weeks, so at the moment I would recommend just treating the pain and seeing what happens over the next few weeks. If the symptoms persist or get worse referral to neurology for nerve conduction studies would seem to be the best option. Gareth